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This issue came up when trying to assist a user with the questions: What are the required build dependencies of mesa for Debian-based distros? and How do I backport Mesa on Debian Wheezy?.

Mesa on Debian fails to build from source under certain conditions. See the Debian bug report: libdrm-nouveau1a: claims to be 2.4.33, but seems to really be 0.6. I was able to reproduce this building Mesa 9.1.3-1 (from snapshot.debian.org) on Wheezy. I get the following error message:

checking for NOUVEAU... no
configure: error: Package requirements (libdrm_nouveau >= 2.4.33) were not  
met:

Requested 'libdrm_nouveau >= 2.4.33' but version of libdrm_nouveau is 0.6

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables NOUVEAU_CFLAGS
and NOUVEAU_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.

See the full log at gist.github.com.

I'm not sure what is going on here. There is an "explanation" in the bug report, but I don't understand it. Namely:

It's not a bug in the debian libdrm 2.4.33 package. In libdrm git they bumped the soname to 2 and changed the version exported in libdrm_nouveau.pc from 0.6 to 2.4.33 without releasing a new version. Mesa now requires the newer libdrm that hasn't been released yet. In libdrm 2.4.33 the version in libdrm_nouveau.pc is 0.6

http://cgit.freedesktop.org/mesa/drm/commit/?id=292da616fe1f936ca78a3fa8e1b1b19883e343b6 is the commit this all took place today.

The file /usr/lib/x86_64-linux-gnu/pkgconfig/libdrm_nouveau.pc exists on my system. This is a pkg-config file. It has the following contents.

prefix=/usr
exec_prefix=${prefix}
libdir=${prefix}/lib/x86_64-linux-gnu
includedir=${prefix}/include

Name: libdrm_nouveau
Description: Userspace interface to nouveau kernel DRM services
Version: 0.6
Libs: -L${libdir} -ldrm_nouveau
Cflags: -I${includedir} -I${includedir}/libdrm -I${includedir}/nouveau
Requires.private: libdrm

This is presumably where the configure is getting the information that libdrm_nouveau is 0.6.

However, I'm unclear why the version was set to 0.6 when the actual value is 2.4.40-1~deb7u2 (Debian wheezy default). I'm also unsure of the correct way to fix this in the current context - building Mesa 0.9.3.1 on wheezy.

There are two obvious changes one could make which would (probably) allow Mesa to build.

  1. Change the version number in /usr/lib/x86_64-linux-gnu/pkgconfig/libdrm_nouveau.pc to 2.4.33 or higher
  2. Alter the Mesa configure script to accept libdrm at version 0.6.

I don't much like either of these alternatives. In the former case, I dislike messing with a running system. It is never clear what effects it may have. In the latter case, changing a build system without properly understanding what effect it will have does not seem like a great idea either.

NOTE: If you want to reproduce the error on Wheezy, you can do the following:

  1. go to http://snapshot.debian.org/package/mesa/9.1.3-1/

  2. download the files:

  3. Run 

    dpkg-source -x mesa_9.1.3-1.dsc

  4. cd into the source directory meda-9.1.3 and run

    debuild -uc -us

    and install missing build dependencies.

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Faheem Mitha
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