Older blog entries for mjg59 (starting at number 211)

One of the strengths of the open source community is that so much happens in the open. It's generally easy to find out what's happening in a project and directly interact with the developers. Code is out in the public. People frown upon closed discussion and implementation. But there's also a cost. Personality conflicts get hidden in the corporate world. We air them in public. And while in some ways that's arguably an advantage, it also results in things like this.

Now, to be fair, I've never been an especially big fan of Sam's work. His journalism generally leans towards lazy sensationalism rather than any attempt to actually understand the issues. He's not especially well versed on the basis of free software (see his assertion that the difference between the cathedral and bazaar development models is about project leadership rather than source code availablity and how people participate). He's managed to mischaracterise my opinions in the past, which means trusting his characterisation of anyone else is somewhat difficult. But that's not the point. Sam's article isn't about facts or analysis. It's about crucifying someone for expressing an opinion that Sam disagreed with.

I don't know Anirudh. From his website, he sounds like a pretty typical young hacker. He's contributing to a project that interests him. He's self taught. He holds strong opinions. And, last week, he published a rant on a topic he cared about - specifically his feeling that the patent concerns about Mono shouldn't prevent people from developing in it, and that RMS's statements about not using Mono harm the free software community more than they help it. I don't agree with all of his arguments. I don't think it was a hugely well structured rant. And, shockingly, telling RMS to fuck off isn't going to achieve a great deal.

But the point wasn't to change the world. People like voicing their opinions. I've done so several times on several occasions on a wide range of topics. People have disagreed with me. People have voiced concerns about the way I've expressed myself. People have flat out told me to stop being a cock. But nobody has attempted to tell me that I haven't earned the right to express that opinion. Nobody has expended four pages to tear me apart for daring to criticise another member of the community. Nobody has dared to call me a coward for deciding that I'd gone too far and modifying or retracting something I've written.

Yet that is precisely what Sam Varghese has done here. And let's be clear here - the use of the word "fuck" is a red herring. Sam is publically humiliating someone because he has his own agenda. He's picking on someone smaller than him because he can. He's explicitly stating that anyone arguing in favour of Mono can expect to be thoroughly abused in front of a large audience. In Sam's world I don't get to criticise the shockingly distasteful sexist remarks RMS made during his GCDS keynote because I didn't write emacs. I don't get to point out that ESR's understanding of racial genetics and natural selection are fundamentally flawed because I don't maintain the jargon file. I don't get to say that I think Ted Tso was wrong about ext4's semantic changes because I've never written a filesystem. And if I do any of these things, I can expect Sam to pop up and do his best to destroy my reputation.

Of course, he won't. Because in Sam's world, it's not actually about whether anyone has achieved great things. It's about whether the targets of his vitriol will be able to stand up for themselves or not. And while the truth is that nobody in the community is above criticism and nobody needs to earn their right to disagree, I doubt that Sam is ever going to show the courage that Anirudh did and publish a public retraction of his astonishing attack.

Shame on you, Sam Varghese.

Syndicated 2009-07-06 17:18:10 from Matthew Garrett

I've had hard drives die before, but this one seems to be doing it in an especially pathological way. It started with the kernel throwing irq timeout errors and then stepped up into actual read errors, culminating in a corrupt journal, a read-only block device and a forced fsck. It's been behaving a little better since then, though occasional io stalls (without any kernel error) suggest that it's having to repeatedly retry some sectors. SMART says it's all fine, so obviously I'm backing it all up now before a new disk arrives tomorrow and I can sort out access to the data centre. Email might be a bit spotty for me until then.

Turns out that running a 2.5" PATA drive for approximately 4 straight years may not have been the best of ideas. Who'd have guessed?

Syndicated 2009-06-25 21:38:42 from Matthew Garrett

I spent last week in the US, during which I discovered that my preconceptions of Albany as a post-industrial wasteland with no redeeming features was incorrect (it's actually a post-industrial wasteland with some decent bars), made minor contributions (mostly in the form of pesto) to a prize winning chalk picture and cycled on the wrong side of the road for the first time in a ridiculous number of years.

But more relevantly, I spent most of the week trapped in Westford. One of the things I've been looking into lately is USB autosuspend, a kernel feature which allows devices to be powered down when they're not in use. This is especially interesting for USB, since it's a poll-based protocol. If the end device is powered up then bus traffic will be generated, even if everything's idle. USB autosuspend allows this to be avoided and thus saves a worthwhile amount of power.

However, drivers need to support USB autosuspend before it's useful. Further, devices need to be able to cope with it. Some older kernel releases had autosuspend enabled by default, leading to all kinds of fun as people discovered that their scanners and printers had stopped working. This was fixed by leaving autosuspend disabled by default for most hardware. The first component that I'm working on is support for drivers to indicate whether or not a given piece of hardware supports autosuspend, allowing it to be enabled by default for that kernel. Handling this at a per-driver level means we shouldn't end up with obnoxious white or blacklists. The second is adding support for autosuspend to more drivers. Right now I'm concentrating on hardware that's common in laptops. There's support for autosuspend in the qcserial and uvc drivers, and some experimental (and unmerged) patches for bluetooth and some other modem drivers. Palm have just released their kernel code, which includes autosuspend support for the cdc-acm driver. I'm working on cleaning these up and getting them into a mergable state, and part of what I was doing in Westford was testing that various pieces of hardware work correctly. The good news is that they seem to, and with a bit of luck we'll try shipping support for a lot of this in F12. If that doesn't end up causing real world problems then it ought to be safe to merge it all to mainline.

The final component of this is handling autosuspend on devices with userspace drivers. Our only real choice there is for packages to ship udev fragments that enable it for working hardware. I've added support to the fprint package in rawhide, which means that fingerprint readers should now be powered down unless they're opened. Nobody seems to have complained yet, so I'm cautiously optimistic that this can be sent upstream without any problems.

Syndicated 2009-06-24 14:07:17 from Matthew Garrett

It's now been over 6 months since Poulsbo hardware with Intel's GMA500 graphics core started shipping in volume. And we're still utterly lacking in any sort of worthwhile driver. It's an impressive turnaround from the recent days when the straightforward recommendation for mobile Linux hardware was "anything that has lots of Intel stuff in lspci", and while the Poulsbo situation in itself doesn't change that hugely it's potentially symptomatic of a worrying trend within parts of Intel.

The first thing to realise here is that, like most large companies, Intel consists of a large number of business units with different priorities. Their open-source technology center has historically had responsibility for providing Linux support for hardware, but this obviously depends on other business units cooperating with them. And there's strong evidence that many of those business units don't get it.

There's been signs of this for some time. Back before the days of the Intel X.org driver gaining native modesetting support, some people ran the Intel embedded graphics driver. This was (is?) a closed X driver that was able to provide native modesetting on platforms that could only otherwise be run at incorrect resolutions. One business unit was shipping a driver that was more functional than the official Intel Linux driver. To the best of my knowledge, none of that code was ever used in the rewritten Intel driver that now provides the same features.

Poulsbo is another example of this. Intel wanted a low-power mobile graphics chipset and chose to buy in a 3D core from an external vendor. IP issues prevent them from releasing any significant information about that 3D core, so the driver remains closed source. The implication is pretty clear - whichever section of Intel was responsible for the design of Poulsbo presumably had "Linux support" as a necessary feature, but didn't think "Open driver" was a required part of that. There's not a lot any other body inside Intel can do once IP-limiting contracts are signed and the hardware's shipping, but it ends up tarnishing the good reputation that other parts of Intel have built up anyway.

And while Poulsbo is the most obvious example of this to date, it's not the only one. Intel recently decided to make the EFI development kit discussion lists private. Various drivers for Moorestown (the followup platform to Poulsbo) have been submitted to the Linux kernel, and while they have the advantage of being GPLed they have the disadvantage of being barely above the level of typical vendor code. Objections that chunks of them simply don't integrate into Linux correctly has done little to get these problems fixed - I still have no real idea how the runtime interface to power management on the SD driver is supposed to be used, but I suspect the answer is probably "badly".

This all makes sense if you assume that there are large groups of people in Intel who don't talk to each other. But to the casual observer it just looks schizophrenic. Explaining to an irate user that the Intel who shipped a closed Linux graphics driver is only barely the same Intel who contribute so much to architectural improvements in the Linux graphics stack doesn't make their hardware work. And while all of this confusion is going on, Intel's competitors are catching up. Atheros are now making significant contributions to the state of Linux wireless. AMD are releasing graphics chipset documentation faster than Intel, and radeon support is improving rapidly.

Is the future going to be one where we can no longer simply say that Intel hardware will Just Work? Is their work on Moblin (easily the most compelling Linux UI for netbooks) going to be wasted on the broader Linux community because it'll mostly end up running on hardware that's not supported by the mainline Linux kernel? Does Intel have a real commitment to open source, or is that being lost in the face of short-term requirements?

Intel need to demonstrate that they have a company-wide understanding of what Linux support actually means or risk losing much of what they've earned over the past few years. I'm desperately hoping that Poulsbo and what we've seen so far of Moorestown are the exception, not the future norm.

Syndicated 2009-06-23 20:41:44 from Matthew Garrett

Palm Pre

I'm in the UK and even if I weren't I wouldn't be using a CDMA phone, but the Palm Pre is undoubtedly an interesting device and so I've spent a short while looking at the root filesystem that can be extracted from the downloadable ROM image. There's some interesting things there. Bear in mind that this could be some QA internal image, so chunks of what I talk about may be wrong - on the other hand it seems to have been produced in May, so it's probably pretty close to what's shipping.

Hardware

As others have figured out by now, the Pre is codenamed Castle and there's some references to another device called Pixie. This is presumably the Eos device that's expected to end up with AT&T. The other interesting thing is that the image contains modem firmware for both CDMA and UMTS. They're shipped as tarballs - extracting them gives you something that looks awfully like the firmware for the Qualcomm Gobi dual-CDMA/HSDPA chipset used in a bunch of modern laptops. The core firmware is an ELF object for 32-bit ARM. It's got references to Qualcomm in it and it's also got an embedded RSA signature which presumably cuts back on the potential for interesting hacking. The

/usr/bin/PmModemUpdater -e < /usr/lib/modem/castleumtsfw.tar

command, executed as root, should flash the UMTS firmware to the modem (castlecdma_evt1_fw.tar is the CDMA firmware). However it should be noted that the MSM6801A baseband used on the Pre seems to be a CDMA-only chip and there's no obvious place on the board for a SIM socket. My assumption is that the GSM models will have a very similar baseband with different radios. Unlocking the device will presumably be similarly difficult to the iphone - someone will need to find a flaw in the Qualcomm firmware that allows the network lock to be skipped. The PmModemFactory command will let you unlock the phone, but you'll need the appropriate code to do so and can (I guess) permanently lock it if you enter the wrong code too often.

The internal flash appears to present as mmc for some reason.

Software

A lot of the software on the Pre is GPLed, and Palm are therefore obliged to provide copies of the appropriate source code to anyone who receives the software (note that receiving the device is not required - if the software is downloadable then the source offer must be made available to anyone who receives the software). The source code is not currently downloadable - instead Palm have included a written offer to supply the source code on request. This satisfies the GPL, but I can't be bothered doing that for the moment so all of this is purely based on examining the binaries.

The full list of applications extracted from the open source information documented included is here.

General

The Pre appears to be an OpenEmbedded-based system. It uses ipkg for package management and the majority of the basic userspace apps are all from Busybox.

Kernel

The Pre's running 2.6.24, and there's various references to Windriver. There's an internal git repository codenamed rockhopper, which is a little odd - rockhopper's the codename for a MIPS-based NEC evaluation board. It's probably coincidental, given that there's only so many species of penguin available. The version string includes "joplin" - there's evidence of this in mailing list posts dating back to last year, so it's not clear whether "joplin" is the entire WebOS kernel project or a codename that covers both the castle and pixie platforms.

The hardware-specific drivers look well-integrated, for the most part using the standard kernel interfaces (backlight, led and so on) - this is a marked contrast to Android, which tends to go its own way in this respect. There's a driver for the OMAP DSP, the exmap code for analysing application memory usage, oprofile for detailed profiling analysis, some crypto code, a driver for an SDIO-attached Marvell wifi chipset and support for being a USB gadget (ie, something that appears as a USB device when plugged into a USB host). Side note - depending on whether the system is a castle or a pixie, the g_composite gadget driver is given a different ID to let the host OS differentiate between the two. castle will appear with a USB id of 0x8002, and pixie 0x8012.

There's nothing else very interesting looking about the kernel. The source code should reveal more.

Booting

The Pre uses upstart as its init application. In contrast to mainstream Linux distributions that still mostly use upstart in sysvinit emulation mode, the Pre appears to be almost entirely based on native upstart events. One of the things they've used this for is to automatically stop various services when the update service is started. Beyond that there's nothing exceptional here, but looking at etc/event.d does give insight into what's running on the device.

Userland

In contast to Android, the Pre uses the standard GNU C library and associated userland. Filesystem layout is pretty typical Linux, with / containing the low level binaries and /usr containing the rest of the OS. The only slightly weird thing is that various utilities exist in both their busybox and full forms, and I'm not entirely clear on why it's shipping things like fsck.ext4 though I guess you could use an ext4 sd card or something.

Audio is handled through pulseaudio, while media is handled by gstreamer. There's a large collection of codecs for the DSP including WMA and h.264, but no obvious ogg support despite libogg and libvorbis being mentioned in the list of open source software shipped. Future plans? Pulled partway through development? Unclear.

ipod emulation

The Pre pretends to be an ipod by switching into a different USB profile (and thus giving the right USB information) and setting up a filesystem that looks like an ipod. It provides a SysInfoExtended file that looks like an ipod. The only terribly interesting things about this are the list of formats (AIFF, MP3, WAV, AAC, AppleLossless, Audible, H.264, MPEG4 and H.264LC), the fact that it supports album art, the fact that it doesn't support Apple's DRM and that the firewire GUID looks like it's probably the same on all Pres. Could Apple break this support in a future version of itunes? Yes, but none of this support is hardcoded in the Pre's hardware - Palm could provide an update that matches. I don't see any real benefit to Apple in breaking the support, and if it could be shown that they were doing it deliberately then there could be potential legal issues.

The code actually looks generic enough that it could probably be made to emulate other USB mass-storage based media players if you wanted to. I have no idea why you'd want to.

misc

There's a PalmOS ROM image for use in the emulator. usr/share/accountservices contains some files with interesting links in - one of them gives a full dump of the PHP setup on a Palm server, which gives some indications of their internal network setup and other things that are probably harmless but companies usually get paranoid over. The flasher application is called Trenchcoat. There's setup code for traffic shaping support - I haven't checked whether this is for application QoS on the device or whether it's intended for use with tethering.

Binutils is shipped. The Pre has an ARM assembler installed by default. The mind faintly boggles. It looks like there's tethering support via the Bluetooth PAN profile (see usr/bin/PmConnectionManager) as well as via USB. IPC is dbus-based rather than using something custom like Android's binder.

Overall

I'm impressed. There's a few rough edges and some obvious short-term hacks, but overall the Pre has the appearance of being a well-engineered distribution. It's recognisably Linux in a way the Android isn't. Since it seems to be possible to gain root by entering the developer mode, I suspect that modifying the firmware image isn't especially difficult. It'll be interesting to see what happens when GSM ones appear.

There's some more information at the pre dev wiki.

Syndicated 2009-06-10 14:41:10 from Matthew Garrett

Antler customer service

In what makes a surprising change from my normal bitching about customer service, I called Antler last week after the rubber coating on the wheels of my luggage disintegrated. I've had that bag for almost 5 years and travelled something like 300,000 miles in that time, so it wasn't an especially surprising result - but the bag had a 7 year warranty covering defects in materials and manufacture, so they picked it up last week and dropped off a new one today. I'm impressed.

Syndicated 2009-06-09 15:24:03 from Matthew Garrett

Thinkpad mixers

Older (up to the *60 series) Thinkpads have a slightly odd mixer setup. There's a mixer stage that sits between the software controllable mixer and the speakers. This is controlled by the firmware in response to the volume keys being hit and can't be prevented by the OS. This is unfortunate, since users are quite enthusiastic about seeing an on-screen display when they hit various keys and if we do the obvious thing and map the volume keys to KEY_VOLUMEUP and KEY_VOLUMEDOWN then they get the OSD but also get their software-controlled mixer changed at the same time as their firmware-controlled mixer. This causes boundless confusion.

Lorne Applebaum recently sent a patch that added an ALSA control to represent the Thinkpad mixer. This means that we can now read and control the Thinkpad-specific hardware without userspace needing any special knowledge. I've gone a little further and sent a followup patch that sends ALSA notifications on button presses. Lennart suggested that it would also be helpful to export dB values and wrote a nice app that measures them - that means that Pulseaudio will be able to set the mixer volume correctly by default.

The only missing part of the puzzle now is getting the OSD back. We still can't map the keys to KEY_VOLUMEUP and KEY_VOLUMEDOWN because that'll still result in two mixers being changed at once. We can't add new keys to indicate that it's a notification event rather than a command, since X can't deal with keycodes greater than 255 (actually 243, since it adds 8 to every kernel keycode for historical hilarity) and we've run out of space. We can't hook off the ALSA notifications because that'll result in the OSD popping up in response to someone dragging a slider in a volume control application. The easiest thing might be to add another ALSA notification that's only triggered if the notification was generated in the kernel and then have userspace listen for that.

Newer Thinkpads appear to have done away with this mixer setup entirely and just send standard volume events. This is a Good Thing.

In other news, I'm off on holiday to Australia for a couple of weeks so may be a bit slow in replying to things.

Syndicated 2009-05-04 00:53:57 from Matthew Garrett

Extended Qualcomm Gobi features

And while I'm on the subject of bitching about hardware support, I had some time to poke at the Qualcomm Gobi hardware a bit more last week. With the aid of Dan Williams of Network Manager fame we identified[1] that the hardware actually does rather more than is obvious from the qcserial driver. There's two extra ports - one is for diagnostics, and the other claims to be an NMEA port. Poking support for these into qcserial is easy enough, but they don't seem especially chatty. The more interesting factor is that the fourth interface on the endpoint is a network device. This isn't unusual in modern hardware - PPP isn't a terribly helpful layering for data transfer, so most recent high speed data cards also provide support for some kind of network device. If you're lucky it's a spec-compliant cdc device. If you've got a gobi then it claims to be a vendor defined class and type and the .inf file for the driver claims that it's a proprietary cdc device. Testing this got cut short by us not actually having an account on Verizon[2], so we don't have any data dumps to work out what the framing looks like.

Interestingly, doing USB dumps revealed that Windows seemed to do everything via the network device. We didn't see any traffic from the other ports, even when attempting to turn on the GPS. So it may also have some magic out of band configuration that doesn't simply use AT commands.

If anyone has this stuff working under Windows, it'd be interesting to try getting some dumps to try to work out what's going on here.

[1] By the simple process of opening the device manager under Windows. Ahem.

[2] The test machine was a Vaio P, which came with a gobi but no SIM slot. Thanks, Sony. Thony.

Syndicated 2009-04-19 00:32:55 from Matthew Garrett

Intel's commitment to open source driver support

By and large, working with Intel is a pleasure. In fact, a while ago I said so in a fairly obvious way. So it's a shame that the support for Poulsbo is still an absolute fucking mess with absolutely no obvious end in sight. Intel's Moblin group (the people who seem to be closest to having responsibility for providing any public Linux support for that hardware, though it's really not clear if they've got any more say in this than I do) have a kernel team that don't want or need a git tree despite having someone who's working on forward porting the driver to modern kernels - probably a job that requires more than one person given what a godawful fucking mess the last public release was, but it'd at least be nice to see what the current state is. Especially since you don't even seem to be able to get the last public release - moblin's git repositories have been rearranged and I can't find the psb-kmod one on their gitweb any more.

The most terribly depressing thing about this is that development is clearly still happening internally. Ubuntu is still being sent tarball releases by Intel, not that the code's getting any better judging by the type of diff involved. This is made even more entertaining by the bug in question being private, leaving no indication whatsoever about what bugs this code is meant to fix or why.

Closed development, random private tarball drops to partners without any public releases or changelogs, no indication of any upstream release, kernel developers entirely unrelated to the development of the driver trying to get code merged so people can actually use the hardware they bought? I'd expect this of some random far-east vendor with no experience in working with Linux, but not a company that's consistently one of the top ten contributors to the kernel and has frequently touted their level of support. There's no meaningful support for Poulsbo. There's just a thin cardboard cutout that's been carefully placed in front of a hole filled with users' hopes and money.

Seriously Intel. Sort it the fuck out.

Syndicated 2009-04-17 00:14:18 from Matthew Garrett

HP EliteBook 2530p

HP apparently decided my 2510p was cursed and replaced it with a 2530p which arrived earlier this week. A bit of playing later and it all seems pretty happy. Backlight control works fine, though you'll need hal-info git to get the hotkeys working out of the box. Sound needs alsa from 2.6.30 or for snd_hda_intel to be loaded with the "model=laptop" parameter. Suspend seems to work out of the box. Hotkeys and rfkill work with hp-wmi. The webcam is supported by the uvcvideo driver. The wwan modem needs qcserial from 2.6.30 and a tool for loading the firmware. It's happy to boot from EFI which probably saves a second or so of boot time. Wireless is iwl5100 and supported by the drivers from Intel. Video is GM45 and worked fine without any tweaking. I've no idea if the modem is supported or not, and I haven't tested the fingerprint reader yet. Grub was slightly unhappy about the idea of an EFI system partition that wasn't declared in a GPT, but that was a two line diff.

I've backported code to rawhide where necessary, so F11 should be released with full support for the hardware. It's quite a nice machine, and seems more solid than the 2510p - I'll see how it's going in a year or so.

Syndicated 2009-04-04 18:05:15 from Matthew Garrett