Tag Archives: fate

About That 32-bit Chroot

Pursuant to my earlier frustration with building and running 32-bit binaries on a 64-bit Linux installation, I have returned to the chroot suggestions set forth in the comments section for that post. I found the DebootstrapChroot HOWTO on the Ubuntu Wiki which seems to be a fairly authoritative solution. Except that it didn’t work right for the many times I was trying to set it up some weeks ago.

I finally got the 32-bit chroot to work tonight. Thus, I am working to migrate the 8 x86_32 configurations over from the VMware machine. All of the gcc versions work when transplanted directly (2.95.3, though, is only happy living in the same path where it originally resided). I am rebuilding a new version of gcc-svn for x86_32 (no reason to migrate an old version when I am constantly updating from gcc SVN anyway). I could probably migrate the Intel C compiler wholesale, but it would probably be better to take this opportunity to finally upgrade from .15 to .17 in the 10.1 series, at least until Carl Eugen Hoyos gives the all-clear to upgrade to the later series (last I heard, it can’t handle the FFmpeg source).

For my future reference, as well as for the benefit of other confused Ubuntu users, I am documenting how I managed to set up the 32-bit chroot environment. I started with the instructions at https://wiki.ubuntu.com/DebootstrapChroot and found them to be mostly accurate but in the wrong order in some places. Mostly, it had to do with the mount points and when to activate them. The original Wiki describes chrooting as root, performing a bunch of apt-get package maintenance (section: “Setting up your chroot with debootstrap”), and only sometime later (section: “Getting stuff (…) working automagically”) setting up special mount points. Then later on (section: “Setting up a dchroot (non-root) environment”), the document recommends replacing the earlier mount points with a new set. Following those instructions in that order always left me with a confused and corrupted chroot setup. I solved the problem by setting up the second set of mount points before performing the initial package maintenance (and never using the first set).

Also, I found it very useful and bandwidth-saving to make a backup copy (‘cp -a /var/chroot/intrepid /var/chroot/fresh.intrepid’) after the cursory debootstrap command. Just in case, you know, it doesn’t work out quite right the first, second, … tenth time, you won’t have to wipe the chroot directory and download all the packages again from scratch.

FATE Comes Through

I was away on a brief Christmas vacation for the last week or so. I was completely absent from ffmpeg-devel list traffic during that time, as well as all email. Occasionally, I would sneak a look at FATE’s main page when I was in the vicinity of an unguarded web browser and clench my fists when I saw that various FFmpeg items were broken, powerless to alert anyone to these facts via email. My tensions eased, however, and my spirits lifted when I would check back a little while later and see that the problems were gone and that the SVN log messages indicated that code was being submitted specifically to address the breakages.

Go team.

However, being away from the action and having FATE as my only window into FFmpeg development reminded me of the various ways the web interface desperately needs to improve. The main fate.multimedia.cx page needs to have a brutally concise summary of the health of the FFmpeg codebase as tested by FATE. I envision that the spirit would be, “Everything is okay… except for the following problems: …”, followed by a list of problems, sorted by newest to oldest.

How to do this? For starters, I have had it on my TODO list for several months now to experiment with some popular PHP web frameworks. I have done enough homework to get over my distaste for the notion of such frameworks and I’m thinking (hoping, really) that one can be of substantial benefit.

Of course, another oft-requested feature is for email notifications when something breaks. Believe me, I really want this too. As you can imagine, this is something I really want to get correct from the start and verify that all the bugs are stamped out. Specifically, I’m paranoid about accidentally spamming a mailing list due to a stupid bug. Also, I want to make sure that such a notification service reports the useful information, where I’m currently defining “useful” as state transitions: report when a build or a test goes from working to broken or vice versa. But I also want to be able to aggregate information about breakages. Example: There are presently 20 FATE configurations. If an SVN commit breaks a test for all the configurations, it would be better for an alert email to report concisely that a recent commit broke a particular test for ALL supported FATE configurations, rather than 20 individual emails representing each configuration, or even one email listing each individual configuration.

It’s a real concern. If I don’t get this right, it’s only going to irritate people right out of the gate and defeat the whole purpose when it goes largely filtered and ignored. I know from whence I speak due to working with similar notification systems on other large codebases.

New and Reinstated Tests

So I set up the RPC testing tool in such a way that it includes not only all 8 Linux/x86_32 configurations, but also the Mac/PPC configuration. So when I launch the RPC tool, I am testing a command line across 21 different combinations of platform/compiler configurations for FFmpeg.

That, my friends, is power.

Thanks to this new tool — nay, superpower — I have efficiently updated and reinstated the following test specs:

Even though I am asking for input from the Mac/PPC build, it’s probably a good thing that it is not part of the overall test environment yet. There are more than a few tests (most RGB colorspace video decoders) for which the Mac/PPC build’s output varies from all the other platforms, even the Linux/PPC configurations. I don’t know where the discrepancy lies.

Further, I have finally gotten back to adding new test specs. Predictably, the major bottleneck now is the web administration interface. Working from my notes in the FATE Test Coverage MultimediaWiki page, I added these tests:

In case I haven’t adequately articulated my case, let me reiterate that this RPC test staging tool is really neat. When testing a spec, I craft the most unremarkable command line (ffmpeg -i file -f framecrc -) and see the results. If there is an endian clash — i.e., all the big endian configurations hold one opinion about the stdout vs. the little endian configurations — I check the native colorspace of the video decoder. If it’s an RGB-based video codec, I refine the command line with a “-pix_fmt rgb24” to normalize the colorspace and dispatch the command again. If the video codec is YUV-based and I know or suspect it involves a DCT, I refine the command with “-idct simple” and send it out again.