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Luc Verhaegen

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PowerVR SGX code leaked. [Nov. 21st, 2014|11:22 pm]
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[Current Location |Rumpelkammer again, finally.]
[mood |Appalled at people, but hopeful.]
[music |Foo Fighters - The colour and the shape - Monkey wrench]

So someone leaked 2011 era PowerVR SGX microcode and user space... And now everyone is pissing themselves like a bunch of overexcited puppies...

I've been fed links from several sides now, and i cannot believe how short-sighted and irresponsible people are, including a few people who should know better.


Having gotten that out of the way, I am writing this blog to put everyone straight and stop the nonsense, and to calmly explain why this leak is not a good thing.

Before i go any further, IANAL, but i clearly do seem to tread much more carefully on these issues than most. As always, feel free to debunk what i write here in the comments, especially you actual lawyers, especially those lawyers in the .EU.

LIBV and the PVR.

Let me just, once again, state my position towards the PowerVR.

I have worked on the Nokia N9, primarily on the SGX kernel side (which is of course GPLed), but i also touched both the microcode and userspace. So I have seen the code, worked with and i am very much burned on it. Unless IMG itself gives me permission to do so, i am not allowed to contribute to any open source driver for the PowerVR. I personally also include the RGX, and not just SGX, in that list, as i believe that some things do remain the same. The same is true for Rob Clark, who worked with PowerVR when at Texas Instruments.

This is, however, not why i try to keep people from REing the PowerVR.

The reason why i tell people to stay away is because of the design of the PowerVR and its driver stack: PVR is heavily microcode driven, and this microcode is loaded through the kernel from userspace. The microcode communicates directly with the kernel through some shared structs, which change depending on build options. There are sometimes extensive changes to both the microcode, kernel and userspace code depending on the revision of the SGX, customer project and build options, and sometimes the whole stack is affected, from microcode to userspace. This makes the powervr a very unstable platform: change one component, and the whole house of cards comes tumbling down. A nightmare for system integrators, but also bad news for people looking to provide a free driver for this platform. As if the murderous release cycle of mobile hardware wasn't bad enough of a moving target already.

The logic behind me attempting to keep people away from REing the PowerVR is, at one end, the attempt to focus the available decent developers on more rewarding GPUs and to keep people from burning out on something as shaky as the PowerVR. On the other hand, by getting everyone working on the other GPUs, we are slowly forcing the whole market open, singling out Imagination Technologies. At one point, IMG will be forced to either do this work itself, and/or to directly support open sourcing themselves, or to remain the black sheep forever.

None of the above means that I am against an open source driver for PVR, quite the opposite, I just find it more productive to work on the other GPUs amd wait this one out.

Given their bad reputation with system integrators, their shaky driver/microcode design, and the fact that they are in a cut throat competition with ARM, Imagination Technologies actually has the most to gain from an open source driver. It would at least take some of the pain out of that shaky microcode/kernel/userspace combination, and make a lot of peoples lives a lot easier.

This is not open source software.

Just because someone leaked this code, it has not magically become free software.

It is still just as proprietary as before. You cannot use this code in any open source project, or at all, the license on it applies just as strongly as before. If you download it, or distribute it, or whatever other actions forbidden in the license, you are just as accountable as the other parties in the chain.

So for all you kiddies who now think "Great, finally an open driver for PowerVR, let's go hack our way into celebrity", you couldn't be more wrong. At best, you just tainted yourself.

But the repercussion go further than that. The simple fact that this code has been leaked has cast a very dark shadow on any future open source project that might involve the powervr. So be glad that we have been pretty good at dissuading people from wasting their time on powervr, and that this leak didn't end up spoiling many man-years of work.

Why? Well, let's say that there was an advanced and active PowerVR reverse engineering project. Naturally, the contributors would not be able to look at the leaked code. But it goes further than that. Say that you are the project maintainer of such a reverse engineered driver, how do you deal with patches that come in from now on? Are you sure that they are not taken more or less directly from the leaked driver? How do you prove this?

Your fun project just turned from a relatively straightforward REing project to a project where patches absolutely need to be signed-off, and where you need to establish some severe trust into your contributors. That's going to slow you down massively.

But even if you can manage to keep your code clean, the stigma will remain. Even if lawyers do not get involved, you will spend a lot of time preparing yourself for such an eventuality. Not a fun position to be in.

The manpower issue.

I know that any clued and motivated individual can achieve anything. I also know that really clued people, who are dedicated and can work structuredly are extremely rare and that their time is unbelievably valuable.

With the exception of Rob, who is allowed to spend some of his redhat time on the freedreno driver, none of the people working on the open ARM GPU drivers have any support. Working on such a long haul project without support either limits the amount of time available for it, or severely reduces the living standard of the person doing so, or anywhere between those extremes. If you then factor in that there are only a handful of people working on a handful of drivers, you get individuals spending several man-years mostly on their own for themselves.

If you are wondering why ARM GPU drivers are not moving faster, then this is why. There are just a limited few clued individuals who are doing this, and they are on their own, and they have been at it for years by now. Think of that the next time you want to ask "Is it done yet?".

This is why I tried to keep people from REing the powerVR, what little talent and stamina there is can be better put to use on more straightforward GPUs. We have a hard enough time as it is already.

Less work? More work!

If you think that this leaked driver takes away much of the hard work of reverse engineering and makes writing an open source driver easy, you couldn't be more wrong.

This leak means that here is no other option left apart from doing a full clean room. And there need to be very visible and fully transparent processes in place in a case like this. Your one man memory dumper/bit-poker/driver writer just became at least two persons. One of them gets to spend his time ogling bad code (which proprietary code usually ends up being), trying to make sense of it, and then trying to write extensive documentation about it (without being able to test his findings much). The other gets to write code from that documentation, but also little more. Both sides are very much forbidden to go back and forth between those two positions.

As if we ARM GPU driver developers didn't have enough frustration to deal with, and the PVR stack isn't bad enough already, the whole situation just got much much worse.

So for all those who think that now the floodgates are open for PowerVR, don't hold your breath. And to those who now suddenly want to create an open source driver for the powervr, i ask: you and what army?

For all those who are rinsing out their shoes ask yourself how many unsupported man-years you will honestly be able to dedicate to this, and whether there will be enough individuals who can honestly claim the same. Then pick your boring task, and then stick to it. Forever. And hope that the others also stick to their side of this bargain.


What have we come to?

The leaked source code of a proprietary graphics driver is not something you should be spreading amongst your friends for "Lolz", especially not amongst your open source graphics driver developing friends.

I personally am not too bothered about the actual content of this one, the link names were clear about what it was, and I had seen it before. I was burned before, so i quickly delved in to verify that this was indeed SGX userspace. In some cases, with the links being posted publicly, i then quickly moved on to dissuade people from looking at it, for what limited success that could have had.

But what would i have done if this were Mali code, and the content was not clear from the link name? I got lucky here.

I am horrified about the lack of responsibility of a lot of people. These are not some cat pictures, or some nude celebrities. This is code that forbids people from writing graphics drivers.

But even if you haven't looked at this code yet, most of the damage has been done. A reverse engineered driver for powervr SGX will now probably never happen. Heck, i just got told that someone even went and posted the links to the powerVR REing mailinglist (which luckily has never seen much traffic). I wonder how that went:
Are you the guys doing the open source driver for PowerVR SGX?
I have some proprietary code here that could help you speed things along.
Good luck!

So for the person who put this up on github: thank you so much. I hope that you at least didn't use your real name. I cannot imagine that any employer would want to hire anyone who acts this irresponsibly. Your inability to read licenses means that you cannot be trusted with either proprietary code or open source code, as you seem unable to distinguish between them. Well done.

The real culprit is of course LG, for crazily sticking the GPL on this. But because one party "accidentally" sticks a GPL on that doesn't make it GPL, and that doesn't suddenly give you the right to repeat the mistake.

Last months ISA release.

And now for something slightly different...

Just over a month ago, there was the announcement about Imagination Technologies' new SDK. Supposedly, at least according to the phoronix article, Imagination Technologies made the ISA (instruction set architecture) of the RGX available in it.

This was not true.

What was released was the assembly language for the PowerVR shaders, which then needs to be assembled by the IMG RGX assembler to provide the actual shader binaries. This is definitely not the ISA, and I do not know whether it was Alexandru Voica (an Imagination marketing guy who suddenly became active on the phoronix forums, and who i believe to be the originator of this story) or the author of the article on Phoronix who made this error. I do not think that this was bad intent though, just that something got lost in translation.

The release of the assembly language is very nice though. It makes it relatively straightforward to match the assembly to the machine code, and takes away most of the pain of ISA REing.

Despite the botched message, this was a big step forwards for ARM GPU makers; Imagination delivered what its customers need (in this case, the ability to manually tune some shaders), and in the process it also made it easier for potential REers to create an open source driver.

Looking forward.

Between the leak, the assembly release, and the market position Imagination Technologies is in, things are looking up though.

Whereas the leak made a credible open source reverse engineering project horribly impractical and very unlikely, it did remove some of the incentive for IMG to not support an open source project themselves. I doubt that IMG will now try to bullshit us with the inane patent excuse. The (not too credible) potential damage has been done here already now.

With the assembly language release, a lot of the inner workings and the optimization of the RGX shaders was also made public. So there too the barrier has disappeared.

Given the structure of the IMG graphics driver stack, system integrators have a limited level of satisfaction with IMG. I really doubt that this has improved too much since my Nokia days. Going open source now, by actively supporting some clued open source developers and by providing extensive NDA-free documentation, should not pose much of a legal or political challenge anymore, and could massively improve the perception of Imagination Technologies, and their hardware.

So go for it, IMG. No-one else is going to do this for you, and you can only gain from it!
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ARM Mali Midgard, as featured on Anandtech. [Jul. 16th, 2014|12:40 pm]
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[Current Location |Rumpelkammer]
[music |Arms and Sleepers - Antwerp]

Anandtech recently went all out on the ARM midgard architecture (Mali T series). This was quite astounding, as ARM MPD tends to be a pretty closed shop. The Anandtech coverage included an in-depth view of the Mali Midgard GPU, a (short) Q&A session with Jem Davies (the head honcho of ARM MPD, ARMs Media Processing Division, the part of ARM that develops the Mali and display and video engines) and a google hangout with Jem Davies a week later.

This set of articles does not seem like the sort of thing that ARM MPD would have initiated itself. Since both Imagination Technologies and NVidia did something similar months earlier, my feeling is that this was either initiated by Anand Lal Shimpi himself, or that this was requested by ARM marketing in response to the other articles.

Several interesting observations can be made from this though, especially from the answers (or sometimes, lack thereof) to the Q&A and google hangout sessions.

Hiding behind Linaro.

First off, Mr Davies still does not see an open source driver as a worthwhile endeavour for ARM MPD, and this is a position that hasn't changed since i started the lima driver, when my former employer went and talked to ARM management. Rumour has it that most of ARMs engineers both in MPD and other departments would like this to be different, and that Mr Davies is mostly alone with his views, but that's currently just hearsay. He himself states that there are only business reasons against an open source driver for the mali.

To give some weight to this, Mr Davies stated that he contributed to the linux kernel, and i called him out on that one, as i couldn't find any mention of him in a kernel git tree. It seems however that his contributions are from during the Bitkeeper days, and that the author trail on those changes probably got lost. But, having contributed to a project at one point or another is, to me, not proof that one actively supports the idea of open source software, at best it proves that adding support to the kernel for a given ARM device or subsystem was simply necessary at one point.

Mr Davies also talked about how ARM is investing a lot in linaro, as a proof of ARMs support of open source software. Linaro is a consortium to further linux on ARM, so per definition ARM plays a very big role in it. But it is not ARM MPD that drives linaro, it is ARM itself. So this is not proof of ARM MPD actively supporting open source software. Mr Davies did not claim differently, but this distinction should be made very clear in this context.

Then, linaro can be described as an industry consortium. For non-founding members of a consortium, such a construction is often used to park some less useful people while gaining the priviledge to claim involvement as and when desired. The difference to other consortiums is that most of the members come from a deeply embedded background, where the word "open" never was spoken before, and, magically, simply by having joined linaro, those deeply embedded companies now feel like they succesfully ticked the "open source" box on their marketing checklist. Several of linaros members are still having severe difficulty conforming to the GPL, but they still proudly wear the linaro badge as proof of their open source...ness?

As a prominent member of the sunxi community, I am most familiar with Allwinner, a small chinese cheap SoC designer. At the start of the year, we were seeing some solid signs of Allwinner opening up to our community directly. In March however, Allwinner joined linaro and people were hopeful that this meant that a new era of openness had started for Allwinner. As usual, I was the only cynical voice and i warned that this could mean that Allwinner now wouldn't see the need to further engage with us. Ever since, we haven't been able to reach our contacts inside Allwinner anymore, and even our requests for compliance with the GPL get ignored.

Linaro membership does not absolve from limited open source involvement or downright license violation, but for many members, this is exactly how it is used. Linaro seems to be a get-out-of-jail-free card for several of its members. Linaro membership does not need to prove anything, linaro membership even seems to have the opposite effect in several cases.

ARM driving linaro is simply no proof that ARM MPD supports open source software.

The patent excuse.

I am amazed that people still attempt to use this as an argument against open source graphics drivers.

Usually this is combined with the claim that open source drivers are exposing too much of the inner workings of the hardware. But this logic in itself states that the hardware is the problem, not the software. The hardware itself might or might not have patent issues, and it is just a matter of time before the owner of said breached patents will come a-knocking. At best, an open source driver might speed up the discovery of said issues, but the driver itself never is the cause, as the problems will have been there all along.

One would actually think that the Anandtech article about the midgard architecture would reveal more about the hardware, and trigger more litigation, than the lima driver could ever do, especially given how neatly packaged an in depth anandtech article is. Yet ARM MPD seemed to have had no issue with exposing this much information in their marketing blitz.

I also do not believe that patents are such a big issue. If graphics hardware patents were such big business, you would expect that an industry expert in graphics, especially one who is a dab hand at reverse engineering, would be contacted all the time to help expose potential patent issues. Yet i never have been contacted, and i know of no-one who ever has been.

Similarly. the first bits of lima code were made available 2.5 years ago, with bits trickling out slowly (much to my regret), and there are still several unknowns today. If lima played any role in patent disputes, you would again expect that i would be asked to support those looking to assert their patents. Again, nothing.

GPU Patents are just an excuse, nothing more.

When I was at SuSE, we freed ATI for AMD, and we never did hear that excuse. AMD wanted a solid open source strategy for ATI as ATI was not playing ball after the merger, and the bad publicity was hurting server (CPU) sales. Once the decision was made to go the open source route, patents suddenly were not an issue anymore. We did however have to deal with IP issues (or actually, AMD did - we made very sure we didn't get anything that wasn't supposed to be free), such as HDCP and media decoding, which ATI was not at liberty to make public. Given the very heated war that ATI and Nvidia fought at the time, and the huge amount of revenue in this market, you would think that ATI would be a very likely candidate for patent litigation, yet this never stood in the way of an open source driver.

There is another reason as to why patents are that popular an excuse. The words "troll" and "legal wrangling" are often sprinkled around as well so that images of shady deals being made by lawyers in smokey backrooms usually come to mind. Yet we never get to hear the details of patent cases, as even Mr Davies himself states that ARM is not making details available of ongoing cases. I also do not know of any public details on cases that have been closed already (not that i have actively looked - feel free to enlighten me). Patents are a perfect blanket excuse where proof apparently does not seem to be required.

We open source developers are very much aware of the damage that software patents do, and this makes the patent weapon perfect for deployment against those who support open source software. But there is a difference between software patents and the patent cases that ARM potentially has to deal with on the Mali. Yet we seem to have made patents our own kryptonite, and are way too easily lulled into backing off at the first mention of the word patent.

Patents are a poor excuse, as there is no direct relationship between an open source driver and the patent litigation around the hardware.

The Resources discussion.

As a hardware vendor (or IP provider) doing a free software driver never is for free. A lot of developer time does need to be invested, and this is an ongoing commitment. So yes, a viable open source driver for the Mali will consume some amount of resources.

Mr Davies states that MPD would have to incur this cost on its own, as MPD seems to be a completely separate unit and that further investment can only come from profit made within this group. In light of that information, I must apologize for ever having treated ARM and ARM MPD as one and the same with respect to this topic. I will from now on make it very clear that it is ARM MPD, and ARM MPD alone, that doesn't want an open source mali driver.

I do believe that Mr Davies his cost versus gain calculations are too direct and do not allow for secondary effects.

I also believe that an ongoing refusal to support an open source strategy for Mali will reflect badly on the sale of ARM processors and other IP, especially with ARM now pushing into the server market and getting into intel territory. The actions of ARM MPD do affect ARM itself, and vice versa. Admittedly, not as much as some with those that more closely tie the in-house GPU with the rest of the system, but that's far from an absolute lack of shared dependency and responsibility.

The Mali binary problem.

One person in the Q&A section asked why ARM isn't doing redistributable drivers like Nvidia does for the Tegra. Mr Davies answered that this was a good idea, and that linaro was doing something along those lines.

Today, ironically, I am the canonical source for mali-400 binaries. At the sunxi project, we got some binaries from the Cubietech people, built from code they received from allwinner, and the legal terms they were under did not prevent them from releasing the built binaries to the public. Around them (or at least, using the binaries as a separate git module) I built a small make based installation system which integrates with ARMs open source memory manager (UMP) and even included a quick GLES test from the lima tests. I stopped just short of debian packaging. The sunxi-mali repository, and the wiki tutorial that goes with it, now is used by many other projects (like for instance linux-rockchip) as their canonical source for (halfway usable) GPU support.

There are several severe problems with these binaries, which we have either fixed directly, have been working around or just have to live with. Direct fixes include adding missing library dependencies, and hollowing out a destructor function which made X complain. These are binary hacks. The xf86-video-fbturbo driver from Siarhei Siamashka works around the broken DRI2 buffer management, but it has to try to autodetect how to work around the issues, as it is differently broken on the different versions of the X11 binaries we have. Then there is the flaky coverage, as we only have binaries for a handful of kernel APIs, making it impossible to match them against all vendor provided SoC/device kernels. We also only have binaries for fbdev or X11, and sometimes for android, mostly for armhf, but not always... It's just one big mess, only slightly better than having nothing at all.

Much to our surprise, in oktober of last year, ARM MPD published a howto entry about setting up a working driver for mali midgard on the chromebook. It was a step in the right direction, but involved quite a bit off faff, and Connor Abbott (the brilliant teenager REing the mali shaders) had to go and pour things into a proper git repository so that it would be more immediately useful. Another bout of insane irony, as this laudable step in the right direction by ARM MPD ultimately left something to be desired.

ARM MPD is not like ATI, Nvidia, or even intel, qualcomm or broadcom. The Mali is built into many very different SoC families, and needs to be integrated with different display engines, 2D engines, media engines and memory/cache subsystems.

Even the distribution of drivers is different. From what i understand, mali drivers are handled as follows. The Mali licensees get the relevant and/or latest mali driver source code and access to some support from ARM MPD. The device makers, however, only rarely get their hands on source code themselves and usually have to make do with the binaries provided by the SoC vendor. Similarly, the device maker only rarely gets to deal with ARM MPD directly, and usually needs to deal with some proxy at the SoC vendor. This setup puts the responsibility of SoC integration squarely at the SoC vendor, and is well suited for the current mobile market: one image per device at release, and then almost no updates. But that market is changing with the likes of Cyanogenmod, and other markets are opening or are actively being opened by ARM, and those require a completely different mode of operation.

There is gap in Mali driver support that ARM MPDs model of driver delivery does not cater for today, and ARM MPD knows about this. But MPD is going to be fighting an upbill battle to try to correct this properly.

Binary solutions?

So how can ARM MPD try to tackle this problem?

Would ARM MPD keep the burden of making suitable binaries available solely with SoC vendors or device makers? Not likely as that is a pretty shakey affair that's actively hurting the mali ecosystem. SoCs for the mobile market have incredibly short lives, and SoC and device software support is so fragmented that these vendors would be responsible for backporting bugfixes to a very wide array of kernels and SoC versions. On top of that, those vendors would only support a limited subset of windowing systems, possibly even only android as this is their primary market. Then, they would have to set up the support infrastructure to appropriately deal with user queries and bug reports. Only very few vendors will end up even attempting to do this, and none are doing so today. In the end, any improvement at this end will bring no advantages to the mali brand or ARM MPD. If this path is kept, we will not move on from the abysmal situation we are in today, and the Mali will remain to be seen as a very fragmented product.

ARM MPD has little other option but to try to tackle this itself, directly, and it should do so more proactively than by hiding behind linaro. Unfortunately, to make any real headway here, this means providing binaries for every kernel driver interface, and the SoC vendor changes to those interfaces, on top of other bits of SoC specific integration. But this also means dealing with user support directly, and these users will of course spend half their time asking questions which should be aimed at the SoC vendor. How is ARM MPD going to convince SoC vendors to participate here? Or is ARM MPD going to maintain most of the SoC integration work themselves? Surely it will not keep the burden only at linaro, wasting the resources of the rest of ARM and of linaro partners?

ARM MPD just is in a totally different position than the ATIs and Nvidias of this world. Providing binaries that will satisfy a sufficient part of the need is going to be a huge drain on resources. Sure, MPD is not spending the same amount of resources on optimizing for specific setups and specific games like ATI or Nvidia are doing, but they will instead have to spend it on the different SoCs and devices out there. And that's before we start talking about different windowing infrastructure, beyond surfaceflinger, fbdev or X11. Think wayland, mir, even directFB, or any other special requirements that people tend to have for their embedded hardware.

At best, ARM MPD itself will manage to support surfaceflinger, fbdev and X11 on just a handful of popular devices. But how will ARM MPD know beforehand which devices are going to be popular? How will ARM MPD keep on making sure that the binaries match the available vendor or device kernel trees? Would MPD take the insane route of maintaining their own kernel repositories with a suitable mali kernel driver for those few chosen devices, and backporting changes from the real vendor trees instead? No way.

Attempting to solve this very MPD specific problem with only binaries, to any degree of success, is going to be a huge drain on MPD resources, and in the end, people will still not be satisfied. The problem will remain.

The only fitting solution is an open source driver. Of course, the Samsungs of this world will not ship their flagship phones with just an open source GPU driver in the next few years. But an open source driver will fundamentally solve the issues people currently have with Mali, the issues which fuel both the demand for fitting distributable binaries and for an open source driver. Only an open source driver can be flexible and cost-effective enough to fill that gap. Only an open source driver can get silicon vendors, device makers, solution creators and users chipping in, satisfying their own, very varied, needs.

Change is coming.

The ARM world is rapidly changing. Hardware review sites, which used to only review PC hardware, are more and more taking notice of what is happening in the mobile space. Companies that are still mostly stuck in embedded thinking are having to more and more act like PC hardware makers. The lack of sufficiently broad driver support is becoming a real issue, and one that cannot be solved easily or cheaply with a quick binary fix, especially for those who sell no silicon of their own.

The Mali marketing show on Anandtech tells us that things are looking up. The market is forcing ARM MPD to be more open, and MPD has to either sink or swim. The next step was demonstrated by yours truly and some other very enterprising individuals, and now both Nvidia and Broadcom are going all the way. It is just a matter of time before ARM MPD has to follow, as they need this more than their more progressive competitors.

To finish off, at the end of the Q&A session, someone asked: "Would free drivers gives greater value to the shareholders of ARM?". After a quick braindump, i concluded "Does ARMs lack of free drivers hurt shareholder value?" But we really should be stating "To what extent does ARMs lack of free drivers hurt shareholder value?".
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The Raspberry Pi, en route to becoming a proper open platform. [Mar. 5th, 2014|05:32 pm]
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[Current Location |Rumpelkammer]
[mood |happyhappy]
[music |Fatboy Slim - We've come a long way baby - Praise you]

Like most, I was taken by surprise last weekend, I never expected this to happen, at all.

Given that I was the one to poke a rather big hole in the Raspberry Pi image a year and a half ago, and since i have been playing a bit of a role in freeing ARM GPUs these last few years, I thought I'd say a few words on how I see things, and why I said what I said back then, and why I didn't say other things.

It has become a bit of a long read, but this it's a eventful story that spans about two years.

Getting acquainted.

I talked about the lima driver at linuxtag in may 2012. As my contract work wasn't going any where real, I spent two weeks of codethink time (well, it's not as if I ever did spent just 8h per day working on lima) on getting the next step working with lima, so I had something nice to demo at Linuxtag. During that bringup, I got asked to form a plan of attack for freeing the Raspberry Pi GPU, for a big potential customer. Just after my lima talk at the conference, I downloaded some code and images through the linuxtag wifi, and set about finding the shader compiler on the train on the way back.

I am not one for big micro-managed teams where constant communication is required. I am very big on structure and on finding natural boundaries (which is why you have the term modesetting and the structured approach to developing display drivers today). I tend to split up a massive task along those natural boundaries, and then have clued folks take full control and responsibility of those big tough subtasks. This is why I split the massive task of REing a GPU between the command stream side and the shader compiler. This is the plan of attack that I had formed in the first half of 2011 for Mali (which we are still sticking to today), and I was of course looking to repeat that for the RPi.

On the train, I disassembled glCompileShader from the VideoCore userspace binary, and found the code to be doing surprisingly little. It quickly went down to some routines which were used by pretty much all gl and egl calls. And those lower routines were basically taking in some ids and some data, and then passing it to the kernel. A look at the kernel code then told me that there was nothing but passing data through happening at that side...

There was nothing real going on, as all the nifty bits were running somewhere else.

In the next few days, I talked to some advanced RPi users on IRC, and we figured out that even the bootloader runs on the Videocore and that that brings up the ARM core. A look at the 3 different binary blobs, for 3 different memory divisions between the ARM and the VideoCore, revealed that they were raw blobs, running directly on the videocore. Strings were very clearly visible, and what was immediately clear is that it was mostly differences in addresses between the 3 blobs. Apart from the addresses, nothing was immediately apparent, apart from the fact that even display code was done by the Videocore. I confirmed with Ben Brewer, who was then working on the shaders for Lima, and who has a processor design background.

The news therefor wasn't good. The Raspberry Pi is a completely closed system with a massive black box pulling all the strings. But at least it is consistently closed, and there is only limited scope for making userspace and 'The Blob' getting out of sync, unlike the PowerVR, where userspace, kernel and microcode are almost impossible to keep in sync.

So I wrote up the proposal for the potential customer (you know who you are), basically a few manmonths of busywork (my optimistic estimate doubled, and then doubled again, as I never do manage to keep my own optimistic timelines) to free the userspace shim, and a potential month for Ben for poking at the videocore blobs. Of course, I never heard back from codethink sales, which was expected with news that was this bad.

I decided to stay silent about the Raspberry Pi being such a closed system, at least for a few weeks. For once, this customer was trying to do The Right Thing by talking to the right people, instead of just making big statements, no matter what damage they cause or what morals they breach. I ended up being quite busy in the next few months and I kind of forgot about making some noise. This came back to haunt me later on.

The noise.

So on oktober 24th of 2012, the big announcement came. Here is the excerpt that I find striking:
"[...] the Raspberry Pi is the first ARM-based multimedia SoC with
fully-functional, vendor-provided (as opposed to partial, reverse engineered)
fully open-source drivers, and that Broadcom is the first vendor to open their
mobile GPU drivers up in this way. We at the Raspberry Pi Foundation hope to
see others follow."
While the text of the announcement judiciously talks about "userland" and "VideoCore driver code which runs on the ARM", it all goes massively downhill with the above excerpt. Together wit the massive cheering coming from the seemingly very religious RPi community, the fact that the RPis SoC was a massively closed system was completely drowned out.

Sure, this release was a very good step in the right direction. It allowed people to port and properly maintain the RPi userspace drivers, and took away a lot of the overhead for integration. But the above statement very deliberately brushed the truth about the BCM2835 SoC under the carpet, and then went on to brashly call for other vendors to follow suit, even though those others had chosen very different paths in their system design, and did not depend on a massive all-controlling black box.

I was appalled. Why was this message so deliberately crafted in what should be a very open project? How could people be so shortsighted and not see the truth, even with the sourcecode available?

What was even worse was the secondary message here. To me, it stated "we are perfectly happy with the big binary blob pulling the strings in the background". And with their call to other vendors, they pretty much told them: "keep the real work closed, but create an artificial shim to aid porting!". Not good.

So I went and talked to the other guys on the #lima channel on irc. The feeling amongst the folks in our channel was pretty uniform one of disgust. At first glance, this post looked as a clear and loud message to support open drivers, it only looked like that on the absolute surface. Anyone who would dig slightly deeper would soon see the truth, and the message would turn into "Keep the blob guys!".

It was clear that this message from the RPi foundation was not helping the cause of freeing ARM GPUs at all. So I decided to react to this announcement.

The shouting

So I decided to go post in the broadcom forums, and this is what I wrote:
Erm… Isn’t all the magic in the videocore blob? Isn’t the userland code you
just made available the simple shim that passes messages and data back and forth
to the huge blob running on the highly proprietary videocore dsp?

– the developer of the lima driver.
Given the specific way in which the original RPI foundation announcement was written, i had expected all from the RPI foundation itself to know quite clearly that this was indeed just the shim driver. The reminder of me being the lima driver developer, should've taken away any doubt about me actually knowing what i was talking about. But sadly, these assumptions were proven quite wrong when Liz Upton replied:

There’s some microcode in the Videocore – not something you should confuse with an
ARM-side blob, which could actually prevent you from understanding or modifying
anything that your computer does. That microcode is effectively firmware.
She really had no idea to what extent the videocore was running the show, and then happily went and argued with someone whom most people would label an industry expert. Quite astounding.

Things of course went further downhill from there, with several RPI users showing themselves from their best side. Although I did like the comment about ATI and ATOMBIOS, some people at least hadn't forgotten that nasty story.

All-in-all, this was truly astounding stuff, and it didn't help my feeling that the RPI foundation was not really intending to do The Right Thing, but instead was more about making noise, under the guise of marketing. None of this was helping ARM GPUs or ARM userspace blobs in any way.

More shouting

What happened next was also bad. Instead of sticking to the facts, Dave Airlie went and posted this blog entry, reducing himself to the level of Miss Upton.

A few excerpts:
"Why is this not like other firmware (AMD/NVIDIA etc)?
The firmware we ship on AMD and nvidia via nouveau isn't directly controlling the GPU
shader cores. It mostly does ancillary tasks like power management and CPU offloading.
There are some firmwares for video decoding that would start to fall into the same
category as this stuff. So if you want to add a new 3D feature to the AMD gpu driver
you can just write code to do it, not so with the rPI driver stack."
"Will this mean the broadcom kernel driver will get merged?

This is like Ethernet cards with TCP offload, where the full TCP/IP stack is run on the
Ethernet card firmware. These cards seem like a good plan until you find bugs in their
firmware stack or find out their TCP/IP implementation isn't actually any good. The same
problem will occur with this. I would take bets the GLES implementation sucks, because
they all do, but the whole point of open sourcing something is to allow other to improve
it something that can't be done in this case."
Amazing stuff.

First of all, with the videocore being responsible for booting the bcm2835, and the bcm2835 already being a supported platform in the linux kernel (as of version 3.7), all the damage had been done already. Refusing yet another tiny message passing driver, which has a massive user-base and which will see a lot of testing, then is rather short-sighted. Especially since this would have made it much easier for the massive RPI userbase to use the upstream kernel.

Then there is the fact that this supposed kernel driver would not be a drm driver. It's simply not up to the self-appointed drm maintainer to either accept or refuse this.

And to finish off, a few years ago, Dave forked RadeonHD driver code to create a driver that did things the ATI way (read: much less free, much more dependent on bios bytecode, and with many other corners being implemented the broken ATI way), wasted loads of AMD money, stopped register documentation from coming out, and generally made sure that fglrx still rules supreme today. And all of this for just "marketing reasons", namely the ability to make trump SuSE with noise. With a history like that, you just cannot go and claim the moral high ground on anything anymore.

Like I've stated before, open source software is about making noise, and Dave his blog entry was nothing more and nothing less. Noise breeds more noise in our parts. This is why I decided to not provide a full and proper analysis of the situation back then, as we had lowered ourselves to the level that the RPI foundation had chosen, and nothing I could have said would've improved on that.


I received an email from Eben Upton last friday, where he pointed out the big news. I replied that I would have to take a thorough look first, but then also stated that I didn't expect Eben to email me if this hadn't been the real thing. I then congratulated him extensively.

And congratulations really are in order here.

The Raspberry PI is a global sales phenomenon. It created a whole new market, a space where devices like the Cubieboard and Olimex boards also are in now. It made ARM development boards accessible and affordable, and put a linux on ARM in the hands of 2.5 million people. It is so big that the original goal of the Raspberry Pi, namely that of education, is kind of drowned out. But just the fact that so many of these devices were sold already, will have a bigger educational impact than any direct action towards that goal. This gives the RPI foundation a massive amount of power, so much so, that even the most closed SoC around is being opened now.

But in Oktober of 2012, my understanding was that the RPI foundation wasn't interested in wielding that power to reach those goals which I and many others hold dear. And I was really surprised when it now was revealed that they did, as I had personally given up on this ever happening, and I had assumed that the RPI foundation was not intending to go all the way.

What's there?

After the email from Eben, I joined the #raspberrypi-internals channel on freenode to ask the guys who are REing the VideoCore, to get an expert opinion from those actually working on the hardware.

So what has appeared:
* A user manual for the 3D core.
* Some sample code for a different SoC, but code which which runs on the ARM core and not on the videocore.
* This sample code includes some interesting headers which helps the guys who are REing the Videocore.
* There's a big promise of releasing more about the Videocore and at least providing a properly free bootloader.

These GPU docs and code not only means that Broadcom has beaten ARM, Qualcomm, Nvidia, Vivante and Imagination technologies to the post, it also makes broadcom second only to Intel. (yes, in front of AMD, or should I say ATI, as ATI has run most of the show since 2008).

Then there is the extra info on the videocore and the promise of a fully free bootloader. Yes, there still is the massive dependance on the VideoCore for doing all sorts of important SoC things, but releasing this information takes time, especially since this was not part of the original SoC release process and it has to be made up for afterwards. The future is looking bright for this SoC though, and we really might get to a point where the heavily VideoCore based BCM2835 SoC becomes one of the most open SoCs around.

Today though, the BCM2835 still doesn't hold a candle to the likes of the Allwinner A10 with regards to openness. But the mid to long term difference is that most of Allwinners openness so far was accidental (they are just now starting to directly cooperate with the linux-sunxi community), and Allwinner doesn't own all the IP used in their SoC (ARM owns the GPU for instance, and it is being a big old embedded dinosaur about it too). The RPI SoC not only has very active backing from the SoC vendor, that SoC vendor also happens to be the full owner of the IP at the same time.

The RPI future looks really bright!


I do not like the 10k bounty on getting Q3A going with the freshly released code. I do not think this is the best way to get a solid gpu driver out, as it mostly encourages a single person to make a quick and dirty port of the freshly released code. I would've preferred to have seen someone from the RPI foundation create a kanban with clearly defined goals, and then let the community work off the different work items, after which those work-items are graded and rewarded. But then, it's the RPI foundations money, and this bounty is a positive action overall.

I am more worried about something else. With the bounty and with the promise of a free bootloader, the crazy guys who are REing the VideoCore get demotivated twice. This 10k bounty rules them out, as it calls for someone to do a quick and dirty hack, and not for long hard labour towards The Right Thing. The promise of a free bootloader might make their current work superfluous, and has the potential to halt REing work altogether. These guys are working on something which is or was at least an order of magnitude harder than what the normal GPU REing projects have or had to deal with. I truly hope that they get some direct encouragement and support from the RPI foundation, and that both parties work together on getting the rest of the VideoCore free.

All in all, this Broadcom release is the best news I have heard since I started on the open ARM GPU path, it actually is the best news I've had since AMD accepted our proposal to free the ATI Radeon (back in june 2007). This release fully makes up for the bad communication of Oktober 2012, and has opened the door to making the BCM2835 the most free SoC out there.

So to Eben and the rest of the guys from the RPI Foundation: Well done! You made us all very happy and proud.
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FOSDEM14 lima driver talk. [Feb. 19th, 2014|02:00 pm]
[Tags|, , , , , , , , , , ]
[Current Location |Rumpelkammer]
[mood |Impatient]
[music |Fatboy Slim - We've come a long way baby - Right here, right now]

The FOSDEM organizers have captured more than 16h of video for 22 DevRooms and they are still working hard on getting all of these videos cut and transcoded and put on their site. This is a mammoth task, and some talks in the graphics devroom are still up in the air because of this.

Luckily, some people from the sunxi community took the livestream of sunxi related talks, and produced some quick dumps of it. I have now copied the Mali driver talk over to my fd.o account so that the sunxi server doesn't become too overloaded. Slides are also available.

This talk mentions where i am at with my mesa driver, why i am taking the route i am taking, the importance of SoC communities, and how the lack thereof hampers driver development, and also talks about the company ARM and their stance towards the open driver.

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FOSDEM, and the SuSE bus. [Feb. 6th, 2014|06:16 pm]
[Tags|, , , ]
[Current Location |Rumpelkammer]
[mood |Puzzled]
[music |The Prodigy - The fat of the land - No good]

When i was still at SuSE, Localhorst would rent a Ford S-Max, and stuff it to the brim with openSuSE kit and swag and drive to FOSDEM. I usually was tolerated on board as well, with my sportsbag full of DevRoom kit, provided i sang along to the radio, and didn't mention burger-king. Everyone at SuSE either made their own arrangements, or everyone was stuck on a flight from Nuremberg to Brussels (which was quickly dubbed "The SuSE-Bomber").

After the massive and rather counterproductive layoffs after FOSDEM 2009, SuSE tended to organize a bus for its own employees. And from what i heard, it was a pretty good solution. Imagine a load of happy geeks, from a place in the world with the best beers, stuck on a bus. It made the whole event seem like a school trip, but one where some beers were actually allowed. And, since there usually was tons of extra space on the bus, a load of ex-SuSE guys got to hitch a ride as well. The result was that a lot of SuSE employees visited FOSDEM, and got to catch up on things with some ex-SuSE guys and generally start doing what conferences are for from the second the bus left Nuremberg. Since busses are cheap, this really was a perfect solution, and everyone was happy.

I never took the bus. For FOSDEM, I want to arrive in brussels around suppertime on friday, and leave monday around midday (when the alcohol of the previous night has worn off a bit). The bus tended to arrive around suppertime as well, but would leave again around 19:00 on sunday. Also, i tend to run a devroom and have at least one talk. I need those 5 hours of peace on the train to prepare my talk. But I heard good things about the bus, and that it all was great fun and a bit of a community event before (and after) the big community event.

This year, however, things were different. For a long time, apparently, nobody from the OpenSuSE team was really bothered with FOSDEM. This i find truly amazing, and a really bad sign with respect of where SuSE and openSuSE is apparently heading. From what i have heard, there was always a bit of a plan to get a bus, but it was unclear where the budget would come from, and no-one took any action. I also heard that two weeks before the event, SuSE employees were asked whether they wanted to go to FOSDEM. Now if you do this 2 weeks before the event, with people who often have a wife and kids these days, most will already have made other plans. Then, if you also state that those people who might be interested, also need to have some travel budget left over, and need to get approval in a few days time, you of course only get a handful of people who end up going to the biggest open source event of the planet. I heard the number 8.

8 people from SuSE went to FOSDEM. An absolute disgrace for what once was the leading european linux distribution.

Here is an idea: why not make the bus a community service from the start? Why doesn't OpenSuSE sponsor a bus, one which starts at nuremberg, and perhaps stops in Frankfurt-Flughafen (so some people can grab a smoke and empty their beer-filled bladders), and then continues on to Brussels? Give the SuSE employees 4 weeks early notice to get their seats reserved (which gives them an incentive to think about FOSDEM early on), and then make seat reservation open to anyone who wants to go visit FOSDEM and lives near Nuremberg or Frankfurt? You can even hand the community members a bag of SuSE swag and a frankonian beer.

SuSE would not only do something good for their own employees and makes it easier on them to visit FOSDEM. They would actually sponsor FOSDEM and help boost their openSuSE community.

I am actually surprised that this has to be said, and that idea hasn't been spawned from within the OpenSuSE team itself. But here you go. Now make it happen for next year.
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FOSDEM, the best conference... In the world. [Feb. 5th, 2014|04:51 pm]
[Tags|, , , ]
[Current Location |Rumpelkammer]
[mood |gratefulgrateful]
[music |Underworld - Beaucoup Fish - Jumbo]

Now that my body is well on its road to recovery, it's time to talk about the great success that FOSDEM was, once again.

We had a really nice devroom and pretty good crowds, but the most amazing thing was the recordings and the livestream. The FOSDEM organizers really outdid themselves there.

After the initial announcement of the graphics devroom went out, Martin Peres contacted me and we talked about getting proper recordings from the DevRoom, and briefly looked into what this would end up costing if we were to buy the equipment for it. Our words were barely cold when the FOSDEM organizers announced what can only be seen as absolutely insane: they would try to provide for full recording of everything.

In the end, FOSDEM provided recording in 22 rooms. They had to get 22 mixing desks, 22 sets of microphones, 22 cameras, 44 laptops... This was apparently mostly rented, and apparently, surprise, surprise, there aren't many rental companies which have such an insane amount of kit available.

Apart from some minor issues (like a broken firewire cable in the wine devroom) things worked out amazingly. Only the FOSDEM guys could pull something this insane off. We had all our talks in the Graphics DevRoom streamed out live, with no issues at all.

I would like to thank all the speakers in the graphics devroom, but i particularly would like to thank Martin Peres, who took full control and responsibility of the video equipment. Then there's Marcus Meissner and Thiery Redding who willingly sat in the back of the devroom and handled the recordings themselves, directing the streams, for only meagre rations of water and cookies. Without people stepping up and doing their bit, a devroom like this would not be possible. And the same goes for the whole of FOSDEM.

At the end of the final talk, after i had talked about sunxi_kms, i tried to thank the FOSDEM organizers, and get the remaining audience to clap for them. But i mostly stood there and babbled, at a loss for words, because what the FOSDEM organizers had achieved with this insane goal is simply amazing. And thinking about it now still, i still get quite emotional...

How on earth did they manage to pull this off, on top of organizing the rest of FOSDEM, a FOSDEM which caters for something like 8000 people as it is... It's just not possible!

It's not as if these guys get paid for what they are doing, FOSDEM is a low budget organization, purely based on volunteers. The absolute core of the organization is just a handful of people who have very busy jobs. And yet, they have succeeded where any other organization would have failed. There's no politics or powerplay, there is no money or commerce. There is just the absolute drive to make FOSDEM the best event on the planet, by making small changes every year...

This was my 7th DevRoom this year, and if i can help it there will be another one next year. I am really proud that i am allowed to do my, comparatively little, part as well. Every sunday evening after FOSDEM, after we sit down in the restaurant with the remainders of the graphics devroom, i am physically broken, but i am also one of the happiest people on the planet...

Each year, no matter what happened in the year before, no matter what nasty open source politics or corporate nonsense took place over that year... Each year, the FOSDEM organizers prove that something amazing can happen if only people do their bit, if only people work towards the same selfless goal. Each year, FOSDEM reminds me of why i do what i do, and why i need to keep on doing it.

Thank you.
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Graphics DevRoom at FOSDEM2014. [Oct. 12th, 2013|11:35 pm]
[Tags|, , , , , , , , , , , , , , , ]
[Current Location |Rumpelkammer]
[mood |excitedexcited]
[music |Chris Clark - Vengeance drools]

Yes, there is going to be another exciting DevRoom about graphics on the upcoming FOSDEM.

It's not called the DevRoom this time round, but a hopefully more general Graphics DevRoom. As was the case with the DevRooms before, anything related to graphics drivers and windowing systems goes. While the new name should make it clearer that this DevRoom is about more than just X, it also doesn't fully cover the load either, as this explicitly does include input drivers as well.

Some people have already started wondering why I haven't been whining at them before. Well, my trusted system of blackmailing people into holding talks early on failed this year. The FOSDEM deadline was too early and XDC was too late, so I decided to take a chance, and request a devroom again, in the hope that enough people will make it over to the fantastic madness that is FOSDEM.

After endless begging and grovelling the FOSDEM organizers got so fed up that they gave us two full days again. This means that we will be able to better group things, and avoid a scheduling clash like with the ARM talks last year (where ARM system guys were talking in one room exactly when ARM graphics guys were talking in another). All of this doesn't mean that First Come, First Serve doesn't apply, and if you do not want to hold a talk with a hangover in an empty DevRoom, you better move quickly :)

The FOSDEM organizers have a system called pentabarf. This is where everything is tracked and the schedules are created, and, almost magically, at the other end, all sorts of interesting things fall out, like the unbelievably busy but clear website that you see every year. This year though, it is expected that speakers themselves manage their own details, and that the DevRoom organizers oversee this, so we will no longer use the trusted wiki pages we used before. While i am not 100% certain yet, i think it is best that people who have spoken at the DevRoom (most of whom i will be poking personally anyway) in the past few years first talk to me first before working with pentabarf, as otherwise there will be duplicate accounts which will mean more overhead for everyone. More on that in the actual call for speakers email which will hit the relevant mailing lists soon.

FOSDEM futures for ARM

Connor Abbott and I both have had chromebooks for a long long time. Connor bought his when it first came out, which was even before the last FOSDEM. I bought mine at a time where I thought that Samsung was never going to sell it in germany, and the .uk version arrived on my doorstep 3 days before the announcement for Europe went out. These things have been burning great big holes in our souls ever since, as i stated that we would first get the older Mali models supported properly with our Lima driver, and deliver a solid graphics driver before we lose ourselves again in the next big thing. So while both of us had this hardware for quite a while, we really couldn't touch these nice toys with an interesting GPU at all.

Now, naturally, this sort of thing is a bit tough to impose on teenagers, as they are hormonally programmed to break rules. So when Connor got bored during the summer (as teenagers do), he of course went and broke the rules. He did the unspeakable, and grabbed ARMs standalone shader compiler and started REing the Mali Midgard ISA. When his father is at FOSDEM this year, the two of us will have a bit of 'A Talk' about Connors wild behaviour, and Connor will be punished. Probably by forcing him to finish the beers he ordered :)

Luckily, adults are much better at obeying the rules. Much, much better.

Adults, for instance, would never go off and write a command stream tracer for this out of bounds future RE project. They would never ever dare to replay captured command streams on the chromebook. And they definitely would not spend days sifting through a binary to expose the shader compiler of the Mali Midgard. Such a thing would show weakness in character and would just undermine authority, and I would never stoop so low.

If I had done such an awful thing, then I would definitely not be talking about how much harder capture and replay were, err, would be, on this Mali, and that the lessons learned on the Mali Utgard will be really useful... In future? I would also not be mentioning how nice it would be to work on a proper linux from the get-go. I would also never be boasting at how much faster Connor and I will be at on turning our RE work on T6xx into a useful driver.

It looks like Connor and I will have some very interesting things to own up to at FOSDEM :)
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Intel & Mir: The point-of-view of a graphics driver developing bystander. [Sep. 10th, 2013|01:22 am]
[Tags|, , , , , , , , ]
[Current Location |Rumpelkammer]
[mood |annoyedannoyed]
[music |Amon Tobin - Sordid]

Only a few days ago did I write about how open source software is not about "code or design or doing The Right Thing". "Open source software is about power, politics, corporate affiliation, and loads and loads of noise." I would like to thank Intel for so succinctly underlining that now with their current action.

Before I go any further, this seems to not be Chris Wilsons decision or his preferred solution. Chris wrote the patch which he was told, by unnamed party or parties in Intel, to back out. Also, I personally do not condone the actions taken by Canonical, but, as a graphics driver developer, I find Intels actions far worse. I rather doubt that Intel thought this one through properly.

What's the problem?

As a graphics driver developer, I fail to see the big problem with Mir.

So what if Canonical has decided to reinvent Wayland? Apart from the weird contribution agreement (which will only limit contributions), Mir is fully free software isn't it? Who are they hurting apart from their own resources and their own users? It's not that I am applauding Canonical for their decision, but I really don't see the massive problem here.

Why is Canonical not allowed to do this?

Reinvention galore

I personally really hate things being reinvented all the time. It is the disease that plagues open source software, and that what makes sure that we don't have a growing linux market.

How often have we heard that something is outdated and broken and doesn't fit modern demands anymore? We are then invariably being told that something new is being built afresh, from the lessons learned of what was done "wrong" before, and that in a few months time, everything is going to be fantastic. Sadly, such timeframes never pan out, and while the known "errors" are fixed, everything else gets broken, which then has to be reinvented or ported as well (or which simply remains broken). And then several years down the line, things are still not perfect, and then someone else (or sometimes even the same person) goes off and implements the next great thing from scratch, again.

We never have something that just works, we just go from broken state to broken state. And nobody learns from this, nobody apparently ever states "Hang on, isn't that pretty much the same story we heard 3 years ago?"

To me, as a stupid shortsighted driver developer, Wayland seems like X reinvented. A server/client display architecture with the new lessons learned implemented, but with everything else broken. We've been waiting for getting all those little niggles worked out ever since 2009, and at one point, networking was added to Wayland making it even more of an X replacement.

So then Mir was announced... And suddenly the world was ablaze. Huge flamewars broke out everywhere and effigies of Mark Shuttleworth were getting burned in the forums. I found the Mir move quite ironic, at first, and thought that the outrage was quite out of proportion, but then I read this article. It is a who's who of reinventers, complaining about Canonical reinventing Wayland. I was appalled.

What exactly gives these people the sole monopoly on reinvention?

What is Intel afraid of?

How could Mir possibly threaten Wayland?

Intel is a pretty big company, and it probably has the largest contingent of open source developers devoted to graphics. It employs some of the brightest and most influential people in the business. On top of that, Wayland was there first, has had more time to mature, has had more applications and toolkits ported, and has a much larger mindshare. Most people would think that Waylands future is pretty secure.

So what could possibly be so much better about Mir that makes Mir such a big threat to Wayland that Intels graphics driver developers have to be told not to support XMir at all? Honestly, in the above constellation, how vastly more superior technically does Mir have to be to justify such an action? If Intel really feels that it has to react like this, well, then it might as well just throw in the towel and go Mir immediately, as Wayland clearly must be completely useless.

What a way to oust your own insecurity.

Software Fascism

Intel finds it necessary to play games with their graphics driver, instead of having Wayland battle it out directly with Mir.

This kind of powerplay is quite insidious, and far more damaging than most people would expect. It completely skews the ability of software to compete on a fair and equal grounds, and hurts us all as it is mostly applied by those who are not able to compete properly, or those who feel as if they shouldn't need to bother to compete properly. It tends to favour the least technically advanced and the least morally acceptable.

The best example which I have come across so far is the RadeonHD versus Radeon battle. RadeonHD beat ATI by actually providing a solid open source driver in September 2007, and we at SuSE had a stated goal of being able to ship a solid open source driver on enterprise desktop rollouts. 3 months later, Radeon came around with support for the same hardware. It was technically inferior, and "borrowed" much of the hard work of radeonHD plus some noise added on top. What was worse was how the so-called community used software fascism to artificially boost the Radeon driver. This started out with the refusal of a mailing list at the usual place, hit a low point with RadeonHD being dropped from the build script for the xserver, and sank to whole new levels when, 2 years after the obvious death of the RadeonHD driver, the RadeonHD repository got vandalized (and the whistleblower got tarred and feathered while the perpetrators were commended for their "quick" confession).

So who won?

Well, it definitely was not RadeonHD, as that died early 2009 with Novell laying off a large portion of SuSE developers in Nuremberg. As luck had it, at the same time, AMD experienced serious financial difficulties and did not continue the RadeonHD project with SuSE. But although Radeon did survive, it did not win either. ATI won, AMD (which wanted a proper open source driver, whereas ATI seriously didn't) lost, and we all lost with it. Fglrx still rules supreme today, but now it does not get as much flack as it did before, as the figleaf driver provides some sort of an alternative for those who are unhappy with fglrx. But it goes beyond that, the radeon driver consistently applies or applied the solutions ATI fglrx developers recommended, instead of the empirical solutions we at RadeonHD usually chose, and the radeon driver is not as good as it could be.

Software fascism goes further than just badly skewing competition, and it always is a negative influence on software. Who knows what other bad decisions will make their way into the Intel driver now?

The responsibility of a graphics driver

The main responsibility of a graphics driver is to support the users of your graphics hardware. If you are actually employed by the vendor, your users are those who bought your hardware and who will buy your hardware again if they are satisfied. This is the business case for providing optimal support for your hardware for a given operating system or infrastructure. On top of that, in open source software, the users are more than just the customers, they are also the testers.

Canonicals plan and marketing seem to have worked out quite well over the years, to the extent that half the planet thinks that linux equals ubuntu, and ubuntu probably has the larger part of the linux desktop market. This means that ubuntu users are a sizable portion of Intels userbase, and as a hardware vendor (and only secondarily a maker of display servers), Intel simply cannot afford to refuse to support or even alienate these users. Canonical has decided that Mir will be the primary display server on future Ubuntu releases, and this in turn means that Intel has an obligation to support Mir.

The Xmir patch to the Intel graphics driver seems rather minimal and not very invasive. There also seems or seemed, as the case may be now, direct communication between Intels graphics driver developers and Ubuntus developers. As Mir will ship on the next Ubuntu versions, there will be a large amount of users which will test the Xmir code in the Intel graphics driver. There is no chance that the Xmir code will bitrot for the foreseeable future, and Intels own investment in this code will be minimal.

The real art of writing good drivers is to provide for quick and painless debugging. Graphics hardware is complex, the drivers for this hardware are also complex, and neither is ever perfect, so one has to work hard to maximize the chance for bug resolution. This means easy communication with users, and giving the user an easy route to test changes so that proper feedback can be provided quickly. If you fail to make it easy enough for users, you will simply not get your bugs fixed, and the higher the resolution threshold becomes, the worse your driver will become.

By not carrying this patch, Intel forces Ubuntu users to only report bugs to Ubuntu, which then means that only few bug reports will filter through to the actual driver developers. At the same time, Ubuntu users cannot simply test upstream code which contains extra debugging or potential fixes. Even worse, if this madness continues, you can imagine Intel stating to its customers that they refuse to fix bugs which only appear under Mir, even though there is a very very high chance of these bugs being real driver bugs which are just exposed by Mir.

The reality of the matter is, Intel is hurting its own graphics driver more than it could potentially hurt Mir or Canonical.

The andriodization of linux

The biggest installed base of Linux is android, and it is bigger by many orders of magnitude. Sadly the linux which we call android is little more than the linux kernel and some new-ish (mostly) open source infrastructure on top. While this, to some extent, is quite the boon for open source software, it also holds a major threat. If we are not careful, we get fully locked hardware. We are only sporadically able to enforce the GPL on the kernel, and we have no chance at all to get open source userspace drivers. This limits the usefulness of the now ubiquitous linux hardware out there, and with the way the desktop and mobile are evolving, this will soon limit the availability of hardware for which more-or-less complete open source is available. On top of that, all those electronics companies that are churning out hardware at an amazing rate, they are either unable to see the advantages of actively contributing to open source, or they are having a very hard time in learning how to do so.

This is exactly why I created the lima driver, and why some other brave souls created their respective GPU reverse engineering projects. We recognized this danger, and are sacrificing a large portion of our lives trying to prevent catastrophe. And even though things are not going as fast or as smooth as we expected, we have come a very long way.

Things took a wrong turn a while back though. In an effort to create a stopgap solution, Jolla developer Munk created libhybris, a wrapper library which allows the usage of android drivers on top of glibc, and thus on a normal linux installation. I find this hack pretty dangerous, as it makes all vendors complacent, and it cements the android way of working and the it makes binary drivers the default. Our biggest open source hopes for mobile; Sailfish, Firefox-OS and Ubuntu-Phone Mir readily embraced this way of working.

I have, so far, not seen anything from either Jolla, The Mozilla Foundation or Canonical, along the lines of active support of the route we have chosen with open ARM GPU drivers, and we've been at it for quite some time now. Those companies are more dependent on open source software than your average android vendor, and know how to do things the open source way, but they have fully embraced the binary drivers built for android only, with no signs of them wanting to change this.

The only reason why I favour Wayland over Mir is that Canonical immediately chose the libhybris route with Mir. Wayland currently has patches for libhybris, so soon Wayland sadly will have sunk to Mirs level as well, from a graphics driver point of view.

Intel employs a small army for their open source software, and specifically for their open source graphics driver. But Intel also has other teams working on graphics drivers, and while I am not certain, I do think that Intel ships binary only drivers on their android devices.

Canonical is happy with using libhybris, but currently would prefer to use a proper graphics driver for their future products. This preference now got significantly reduced. Intel now potentially has driven one of the last big users of open source graphics drivers to exclusively using android binaries as well, seriously reducing the relevance of its own OSTC driver developer team in the process.

The low road

Up until now, intel had the moral high ground in the Wayland versus Mir situation. With the simple decision to revert the Xmir patch, this situation now got reversed.

Well done.
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The lima mesa driver runs es2gears. [Sep. 4th, 2013|12:57 am]
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[Current Location |Rumpelkammer]
[mood |melancholic]
[music |Lemon Jelly - Ramblin' man]


Progress is slow but steady on the lima mesa driver, mostly because I am not giving lima as much time as I should. I now have working attributes, uniforms, vertex buffers and even some state is being set correctly. Enough to run es2gears. Here is the video on youtube, there is an older capture with a rotating smoothed cube as well.

This lima mesa driver uses the old-school (but contrary to popular belief, definitely not deprecated) mesa infrastructure, which, with surprisingly little work, allows me to run the mali binary drivers compiler, and allows me to build the lima driver externally. Using the binary compiler would not be possible from gallium, and with some improvements to the (intel developed, and thus intel focused) mesa glsl compiler, it seems that we might have a potent compiler for the mali ISAs as well. This way, the task of bringing up mesa on mali is nicely split, and we will be able to debug the command stream work separately from the shader compiler. I believe that we did lose the ability to run gles1 programs until Connors open-gpu-tools is hooked up to the mesa glsl compiler. This is just a small price to pay, in comparison to the size of the hurdle to take when doing everything in one go.

We are running es2gears at 130fps on the A10, and 310fps on the Exynos for a 300x300 render. Resizing is currently broken, or rather not implemented. I will need to split up the PLBU command stream to be able to do that properly under DRI2 (where resizes happen behind the mesa drivers back). The way DRI2, mesa and the sunxifb X driver now work together also means that i have to wait for jobs to finish (and then usleep for good measure), so there is a lot of potential for speed-up as well. I am not sure yet how things will have to be hacked to keep X from copying the region before rendering is absolutely done, i guess that we will have to hack something into UMP and the sunxifb driver. But a solution will be found, and we should see around a 50% increase in framerate from that, and even much much more if we manage to use overlays. Since we are in control of all the code now, we should theoretically be able to squeeze every last bit of performance out of the GPU, a luxury not offered to the users of the binary X11 driver.

I will now continue implementing textures, so that i can run all the limare egl tests. After that i will clean up the code and push it out. This will include patches to common mesa versions (and mesa packages) to allow building lima against them. Resizing and job interleaving will have to wait until after that, so keep your eyes peeled on this space :)

10 years in.

A few weeks ago, it was the 10th anniversary of my first contribution to X (a small display fix to the via driver). I cannot state that this anniversary was a happy event.

Looking back, I cannot believe that i once thought that in open source software, code, design and doing The Right Thing, both technically and morally, were paramount. Open source software is about power, politics, corporate affiliation, and loads and loads of noise. Noise and misinformation always wins over code, no matter how good this code is or how hard you work at it. I have had to learn this several times over.

This is especially true in the case of forks. Not the git clone variation, but the loud, aggressive and very detrimental community kind. While often technical reasons are claimed to be the cause, this is never ever the case. It always is about politics and power. And code always suffers as a result, and this suffering is never a short term thing, especially on big forks. See, a fork always means a big stink, a lot of noise, and a power vacuum, and this attracts a certain kind of individual. These personalities form the basis of the new community together with those who instigated or accelerated the fork. Good code simply has no chance in such an environment. Bad code and bad design tends to hang around for a long long time, and tends to influence (read, limit) the thinking of any new blood that turns up. On top of that, the bad mentality also tends to linger for many many years. Politics and noise continues to take precedence over code and design, for the foreseeable future.

The only thing to do in case of a fork, is to go play somewhere else, somewhere where a major fork hasn't taken place. If you don't, or if you do not go far enough, you will see your work impacted, especially if you are not willing to let yourself be limited by the existing mentality and powerbalance.

Now if only i wasn't such a stubborn bastard ;)
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Old and new limare code, and management overhead... [Jun. 4th, 2013|03:16 am]
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[Current Location |Rumpelkammer]
[mood |chipperchipper]
[music |Hole - Live through this 04 - Asking for it]

I just pushed updated limare code and a fix to ioquake3.

In almost 160 patches, loads of things change:

  • clean FOSDEM code supporting Q3A timedemo on a limare ioquake3.

  • support for r3p2 kernel and binary userspace as found on the odroid-x series.

  • multiple PP support, allowing for the full power of the mali 400MP4 to be used.

  • fully threaded job handling, so new frames can be set up while the first is getting rendered.

  • multiple textures, in rgb888, rgba8888 and rgb565, with mipmapping.

  • multiple programs.

  • attribute and elements buffer support.

  • loads of gl state is now also handled limare style.

  • memory access optimized scan pattern (hilbert) for PP (fragment shader).

  • direct MBS (mali binary shader) loading for pre-compiled shaders (and OGT shaders!!!).

  • support for UMP (arm's in kernel external memory handler).

  • Properly centered companion cube (now it is finally spinning in place :))

  • X11 egl support for tests.

  • ...

Some of this code was already published to allow the immediate use of the OGT enabled ioquake3. But that branch is now going to be removed, as the new code replaces it fully.

As for performance, this is no better or worse than the FOSDEM code. 47fps on timedemo on the Allwinner A10 at 1024x600. But now on the Exynos 4, there are some new numbers... With the CPU clocked to 2GHz and the Mali clocked to 800MHz (!!!) we hit 145fps at 720p and 127fps at 1080p. But more on that a bit further in this post.

Upcoming: Userspace memory management.

Shortly after FOSDEM, i blogged about the 2% performance advantage over the binary driver when running Q3A.

As you might remember, we are using ARMs kernel driver, and despite all the pain that this is causing us due to shifting IOCTL numbers (whoever at ARM decided that IOCTL numbers should be defined as enums should be laid off immediately) I still think that this is a useful strategy. This allows us to immediately throw in the binary driver, and immediately compare Lima to the binary, and either help hard reverse engineering, or just make performance comparisons. Rewriting this kernel driver, or turning this into a fully fledged DRM driver is currently more than just a waste of time, it is actually counterproductive right now.

But now, while bringing up a basic mesa driver, it became clear that I needed to work on some form of memory management. Usually, you have the DRM driver handling all of that, (even for small allocations i think - not that i have checked). We do not have a DRM driver, and I do not intend to write one in the very near future either, and all I have is the big block mapping that the mali kernel driver offers (which is not bad in itself).

So in the train on the way back from linuxtag this year, I wrote up a small binary allocator to divide up the 2GB of address space that the Mali MMU gives us. On top of that, I now have 2 types of memory, sequential and persistent (next to UMP and external, for mapping the destination buffer into Mali memory), and limare can now allocate and map blocks of either at will.

The sequential memory is meant for per-frame data, holding things like draws and varyings and such, stuff that gets thrown away after the frame has been rendered. This simply tracks the amount of memory used, adds the newly requested memory at the end, and returns an address and a pointer. No tracking whatsoever. Very lightweight.

The persistent memory is the standard linked list type, with the overhead that that incurs. But this is ok, as this memory is meant for shaders, textures and attribute and element buffers. You do not create these _every_ draw, and you tend to reuse them, so it's acceptable if their management is a bit less optimized.

Normally, more management makes things worse, but this memory tracking allowed me to sanitize away some frame specific state tracking. Suddenly, Q3A at 720p which originally ran at 145fps on the exynos, ran at 176fps. A full 21% faster. Quite some difference.

I now have a board with a Samsung Exynos 4412 prime. This device has the quad A9s clocked at 1.7GHz, 2GB LP-DDR2 memory at 880MHz, and a quad PP Mali-400MP4 at 440MHz. This is quite the powerhouse compared to the 1GHz single A8 and single PP Mali-400 at 320MHz. Then, this Exynos chip I got actually clocks the A9s to 2GHz and the mali to a whopping 800MHz (81% faster than the base clock). Simply insane.

The trouble with the exynos device, though, is that there are only X11 binaries. This involves a copy of the rendered buffer to the framebuffer which totally kills performance. I cannot properly compare these X11 binaries with my limare code. So I did take my new memory management code to the A10 again, and at 1024x600 it ran the timedemo at 49.5fps. About a 6% margin over the binary framebuffer driver, or tripling my 2% lead at FOSDEM. Not too bad for increased management, right?

Anyway, with the overclocking headroom of the exynos, it was time for a proper round of benchmarking with limare on exynos.

Benchmark, with a pretty picture!

Limare Q3A benchmark results on exynos4412

The above picture, which I quickly threw together manually, maps it out nicely.

Remember, this is an Exynos 4412 prime, with 4 A9s clocked from 1.7-2.0GHz, 2GB LP-DDR2 at 880MHz, and a Mali-400MP4 which clocks from 440MHz to an insane 800MHz. The test is the quake 3 arena timedemo, running on top of limare. Quake 3 Arena is single threaded, so apart from the limare job handling, the other 3 A9 cores simply sit idle. It's sadly the only good test I have, if someone wants to finish the work to port Doom3 to gles, I am sure that many people will really appreciate it.

At 720p, we are fully CPU limited. At some points in the timedemo (as not all scenes put the same load on cpu and/or gpu), the difference in mali clock makes us slightly faster if the cpu can keep up, but this levels out slightly above 533MHz. Everything else is simply scaling linearly with the cpu clock. Every change in cpu clock is a 80% change in framerate. We end up hitting 176.4fps.

At 1080p, it is a different story. 1080p is 2.25 times the amount of screen real estate of 720p (if that number rings a bell, 2.25MB equals two banks of Tseng ET6x00 MDRAM :p). 2.25 times the amount of pixels that need to pushed out. Here clearly the CPU is not the limiting factor. Scaling linearly from the original 91fps at 440MHz is a bit pointless, as the Q3A benchmark is not always stressing CPU and GPU equally over the whole run. I've drawn the continuation of the 440-533MHz increase, and that would lead to 150fps, but instead we run into 135.1fps. I think that we might be stressing the memory subsystem too much. At 135fps, we are pushing over 1GBps out to the framebuffer, this while the display is refreshing at 60fps, so reading in half a gigabyte. And all of this before doing a single texture lookup (of which we have loads).

It is interesting to see the CPU become measurably relevant towards 800MHz. There must be a few frames where the GPU load is such that the faster CPU is making a distinguishable difference. Maybe there is more going on than just memory overload... Maybe in future i will get bored enough to properly implement the mali profiling support of the kernel, so that we can get some actual GP and PP usage information, and not just the time we spent waiting for the kernel job to return.

ARM Management and the Lima driver

I have recently learned, from a very reliable source, that ARM management seriously dislikes the Lima driver project.

To put it nicely, they see no advantage in an open source driver for the Mali, and believe that the Lima driver is already revealing way too much of the internals of the Mali hardware. Plus, their stance is that if they really wanted an open source driver, they could simply open up their own codebase, and be done.


We can debate endlessly about not seeing an advantage to an open source driver for the Mali. In the end ARMs direct customers will decide on that one. I believe that there is already 'a slight bit of' traction for the general concept of open source software, I actually think that a large part of ARMs high margin products depend on that concept right now, and this situation is not going to get any better with ARMv8. Silicon vendors and device makers are also becoming more and more aware of the pain of having to deal with badly integrated code and binary blobs. As Lima becomes more complete, ARMs customers will more and more demand support for the Lima driver from ARM, and ARM gets to repeat that mantra: "We simply do not see the advantage"...

About revealing the internals of the Mali, why would this be an issue? Or, let me rephrase that, what is ARM afraid of?

If they are afraid of IP issues, then the damage was done the second the Mali was poured into silicon and sold. Then the simple fact that ARM is that apprehensive should get IP trolls' mouths watering. Hey IP Trolls! ARM management believes that there are IP issues with the Mali! Here is the rainbow! Start searching for your pot of gold now!

Maybe they are afraid that what is being revealed by the Lima driver is going to help the competition. If that is the case, then it shows that ARM today has very little confidence in the strength of their Mali product or in their own market position. And even if Nvidia or Qualcomm could learn something today, they will only be able to make use of that two years or even further down the line. How exactly is that going to hurt the Mali in the market it is in, where 2 years is an eternity?

If ARM really believes in their Mali product, both in the Mali's competitivity and in the originality of its implementation, then they have no tangible reason to be afraid of revealing anything about its internals.

Then there is the view that ARM could just open source their own driver. Perhaps they could, it really could be that they have had very strict agreements with their partners, and that ARM is free to do what they want with the current Mali codebases. I personally think it is rather unlikely that everything is as watertight as ARM management imagines. And even then, given that they are afraid of IP issues... How certain are ARMs lawyers that nothing contentious slipped into the code over the years? How long will it take ARMs legal department to fully review this code and assess that risk?

The only really feasible solution tends to be a freshly written driver, with a full development history available publically. And if ARM wants to occupy their legal department, then they could try to match intel (AMD started so well, but ATI threw in the towel so quickly, but luckily the AMD GPGPU guys continued part of it), and provide the Technical Reference Manual and other documents to the Mali. That would be much more productive, especially as that will already be more legal overhead than ARM management would be willing to spare, when they do finally end up seeing the light.

So. ARM management hates us. But guess what. Apart from telling us to change our name (there was apparently the "fear" of a trademark issue with us using Remali, so we ended up calling it Lima instead), there was nothing that they could do to stop us a year and a half ago. And there is even less that ARM can do to stop us today :)

A full 6.0%...
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