Bug#775235: Repeatable failure to start on i386 running under kvm

Bernhard Übelacker bernhardu at vr-web.de
Wed Feb 25 22:07:05 UTC 2015

first a question about this merging with bug #770130 and #776911.
These bugs seem to happen on real hardware with some intel
graphics card and giving an error:
    "*ERROR* pipe A underrun".

But bug #775235 was explicitly opened by Steve McIntyre to be
run inside a i386 KVM and gives an error:
    "LLVM ERROR: Do not know how to split the result of this operator!"

Therefore I wonder if these should really be merged?


Second I searched a little bit further and came across
this patch discussion: https://freedesktop.org/patch/34445/

This is the start of the patch description by Maarten Lankhorst:
    This fixes a crash when llvmpipe tries to use sse instructions,
    but llvm detects a cpu that doesn't support them.
    Fixes for example piglit/bin/amd_seamless_cubemap_per_texture -fbo -auto
    on i386 when run inside "qemu -cpu qemu32", which would otherwise error with:
    "LLVM ERROR: Do not know how to split the result of this operator!"

Looks very similiar to our issue here.
Therefore I build a own local build of libgl1-mesa-dri and that was
successfully solving the issue inside the i386 KVM.

Unfortunately I cannot find this patch ever applied upstream.
The discussion reads (as far as I could follow) that there are
probably better ways to detect CPU features.
Also cannot say which impact it would have on every other systems.


Did some additional starts of the VM (with debian built packages) to verify:
    qemu-system-i386 -cpu core2duo               works 
    qemu-system-i386 -cpu pentium2               works
    qemu-system-i386 --enable-kvm -cpu host      works
    qemu-system-i386 --enable-kvm -cpu kvm32     works
    qemu-system-i386 --enable-kvm -cpu qemu32    fails
    qemu-system-i386 --enable-kvm                fails
    qemu-system-x86_64 --enable-kvm              fails

Unfortunately "qemu32" seems to be the default.

Kind regards,

These steps should make a local build of libgl1-mesa-dri with the mentioned patch applied:
    mkdir mesa; cd mesa
    apt-get source libgl1-mesa-dri
    cd mesa-10.3.2/
    wget "https://freedesktop.org/patch/34445/raw/" -O debian/patches/08_gallivm_force_sse_instructions_for_llvm_3.5+.patch
    echo 08_gallivm_force_sse_instructions_for_llvm_3.5+.patch >> debian/patches/series
    # install build dependencies
    dpkg-buildpackage -b
    cd ..
        dpkg -i libgl1-mesa-dri_10.3.2-1_i386.deb libgl1-mesa-dri-dbg_10.3.2-1_i386.deb

More information about the pkg-gnome-maintainers mailing list