Unity does not support cpus without sse4

[Tobias Lausch]

Unity uses sse4 instructions which are not available on older celeron or pentium cpus.

The instruction being used causing unity to crash is
PEXTRD

In this case one cannot login into the default unity session.
current workaround is to install gnome.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: unity 7.3.2+15.04.20150420-0ubuntu1 [modified: usr/bin/unity]
ProcVersionSignature: Ubuntu 3.19.0-21.21-generic 3.19.8
Uname: Linux 3.19.0-21-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CurrentDesktop: GNOME
Date: Tue Jun 30 14:32:20 2015
InstallationDate: Installed on 2015-06-29 (0 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)

[Tobias Lausch (tobias-lausch-q)]

Bbacktrace of unity crashing due to illegal instruction.

[Sebastien Bacher (seb128)]

Thank you for your bug report. The stacktrace lacks symbols though, could you get one with debug packages. Do you know what instruction is used and shouldn't?

[Tobias Lausch (tobias-lausch-q)]

From the added backtrace we get that pextrd is the illegal instruction and therefore schouldnt be used.

hmm, I'll try again with installed unity-dbgsym.

[Marco Trevisan (Treviño) (3v1n0)]

> hmm, I'll try again with installed unity-dbgsym.

Please install dbg symbols also for compiz and nux.
Thanks

[Tobias Lausch (tobias-lausch-q)]

ok, found and installed the unity-dbgsym and libnux-4.0-0-dbgsym
but that does not change the backtrace, so I assume it's a compiz bug.

I followed https://wiki.ubuntu.com/DebuggingCompiz.
There they say to install compiz-core-dbgsym compiz-plugins-dbgsym compiz-fusion-plugins-main-dbgsym compiz-fusion-plugins-extra-dbgsym compizconfig-backend-gconf-dbgsym libcompizconfig0-dbgsym compiz-gnome-dbgsym

after adding the debug debs

 deb http://ddebs.ubuntu.com vivid main restricted universe multiverse
 deb http://ddebs.ubuntu.com vivid-updates main restricted universe multiverse
 deb http://ddebs.ubuntu.com vivid-proposed main restricted universe multiverse

and running apt-get update. ;-)

But there are not any compiz-dbgsym in the repositories.
any idea?

[Marco Trevisan (Treviño) (3v1n0)]

The only we need are compiz-core-dbgsym compiz-plugins-default-dbgsym compiz-gnome-dbgsym libcompizconfig0-dbgsym

They should all be on ddebs repos.

[Tobias Lausch (tobias-lausch-q)]

sorry, I forgot to look at the pool. none of them is in the ddebs sorted to dist vivid.

fyi the only compiz debug symbol in the debs is compizconfig-backend-kconfig-dbgsym
from http://ddebs.ubuntu.com/dists/vivid/universe/binary-amd64/Packages

[Tobias Lausch (tobias-lausch-q)]

hmm. sorry. no debug symbols for compiz 1:0.9.12.1+15.04.20150410.1-0ubuntu1 available for vivid.

since recompiling compiz on the affected machine will remove the illegal instruction i cannot help you on this any further.

[Marco Trevisan (Treviño) (3v1n0)]

Oh, that's weird!

Actually these should be in main, but I see no trace either on the main's Packages or in the pool, so it seems that something weird is happening on wily. I'll look into that (or maybe seb128 knows more :)).

[Sebastien Bacher (seb128)]

ddebs are on http://ddebs.ubuntu.com/pool/main/c/compiz/ but it seems the vivid ones are missing, the infrastructure has sometime issues (though it got recent improvements) in which case we need no change uploads to generate new imports...

[Tobias Lausch (tobias-lausch-q)]

ok, will you report when they are available on the debs? then i'll redo the backtrace with compiz debug symbols.

[Marco Trevisan (Treviño) (3v1n0)]

Ok, so...

I've prepared a SRU for getting these ddebs built, the branch is building at https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/landing-027/+packages then if you use this PPA (packages should be ready in few minutes), you should be able to get the *-dbgsym packages installed (even before they actually land in distro)

[Launchpad Janitor (janitor)]

[Expired for Compiz because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for Unity because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for compiz (Ubuntu) because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for unity (Ubuntu) because there has been no activity for 60 days.]