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debug: 0.950
mistranslation: 0.941
register: 0.939
permissions: 0.937
graphic: 0.924
PID: 0.918
assembly: 0.915
virtual: 0.914
semantic: 0.912
arm: 0.911
peripherals: 0.909
kernel: 0.906
user-level: 0.904
boot: 0.902
architecture: 0.901
TCG: 0.895
files: 0.892
VMM: 0.891
hypervisor: 0.883
device: 0.877
KVM: 0.873
socket: 0.873
performance: 0.873
i386: 0.868
ppc: 0.847
vnc: 0.840
risc-v: 0.827
network: 0.801
x86: 0.631
llvmpipe i386 crashes when running on qemu64 cpu
I have installed Ubuntu 14.04.2 amd64 with all updates.
I have downloaded the Ubuntu 14.0.4.2 i386 iso (ubuntu-14.04.2-desktop-i386.iso, MD5SUM = a8a14f1f92c1ef35dae4966a2ae1a264).
It does not boot to Unity from QEMU-KVM with the all following commands:
* sudo kvm -m 1536 -cdrom ubuntu-14.04.2-desktop-i386.iso
* sudo kvm -m 1536 -cdrom ubuntu-14.04.2-desktop-i386.iso -vga std
* sudo kvm -m 1536 -cdrom ubuntu-14.04.2-desktop-i386.iso -vga vmware
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: qemu-kvm 2.0.0+dfsg-2ubuntu1.10
ProcVersionSignature: Ubuntu 3.13.0-49.83-generic 3.13.11-ckt17
Uname: Linux 3.13.0-49-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.10
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Apr 27 14:11:31 2015
InstallationDate: Installed on 2015-01-04 (112 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
SourcePackage: qemu
UpgradeStatus: No upgrade log present (probably fresh install)
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Thanks for reporting this bug.
I cannot reproduce this (on my 15.04 host). Can you show exactly how it fails,
showing both the terminal output and attaching (a)
screenshot(s)?
status: incomplete
It still does not boot to Unity.
If you can imagine black QEMU-KVM window - that is a screenshot.
What logs do you want?
Do you get any output on the console where you ran the kvm command?
If you run kvm with "-vnc :1" and then run "gvncviewer localhost:1", does that work better?
Assuming it still breaks under vnc, then, again using gvncviewer, at the top left you can choose "send key -> ctrl-alt-f2". Please do that, then look at the end of /var/log/syslog. Is anything interesting there?
Which window manager are you using on the host? (I vaguely recall the SDL library in the past has had some trouble in certain window managers)
I can reproduce this on a Trusty/14.04 host when using the i386 isos. The amd64 isos work. Also the i386 isos seem to work when not using kvm directly, but through libvirt. The main difference would be that this uses a VNX display instead of direct graphics using SDL (I believe).
Bug exists with Ubuntu 12.04.5 LTS host and Ubuntu 15.10 alpha guest.
Building from upstream allows me to get to get to the purple login screen when clicking 'Try Ubuntu' (not sure why it doesn't automatically login). So perhaps something has changed upstream?
Finally with a little help on debugging unity, I think I see what is going on. The obvious part seemed to be that compiz seems to fail starting. Which turns out to be LLVM-pipe bailing with an obscure error message:
LLVM ERROR: Do not know how to split the result of this operator!
This made me think about the emulated CPU, even more because Xen HVM guests do work with the i386 isos. And really this is the actual problem! So one quick work-around is to force qemu to use a different CPU type. In my test I used the Wily i386 iso and changed the CPU type from the default (QEMU Virtual CPU v2.0.0) into core2duo. And suddenly the live session works.
So next, what is the difference. Beside of name, model, and stepping, it seems the cpuid flags:
Core(TM)2 Duo CPU (emulated) QEMU Virtual CPU v2.0.0
model 15 model 6
stepping 11 stepping 3
cpuid level 10 cpuid level 4
ore(TM)2 Duo CPU (emulated) QEMU Virtual CPU v2.0.0
model 15 model 6
stepping 11 stepping 3
cpuid level 10 cpuid level 4
--> fpu vme de pse tsc msr pae mce
fpu de pse tsc msr pae mce <--
--> cx8 apic sep mtrr pge mca cmov
cx8 apic sep mtrr pge mca cmov <--
--> pat pse36 clflush mmx fxsr sse
pse36 clflush mmx fxsr sse <--
--> sse2 ss syscall nx lm
sse2 syscall nx lm <--
--> constant_tsc pni vmx ssse3
pni vmx <--
--> cx16 x2apic hypervisor
cx16 x2apic popcnt hypervisor <--
--> lahf_lm vnmi ept
lahf_lm vnmi ept <--
So QEMU CPU misses: vme, pat, ss, constant_tsc, and ssse3 but has popcnt. A different host running Xen was also missing ss, constant_tsc, ssse3, and popct. But it had vme and pat and was working with the i386 iso.
That sounds a bit like either vme or pat missing could cause the i386 build of llvmpipe to fail while the exact same cpuid configuration works with the amd64 version of llvmpipe.
Maybe not exactly the cpuid flags seen but in a weird way how qemu builds some structures. I have to dig more there. But it is strange that qemu64 (which is the default cpu type if nothing else is specified) is defined as something based on a AMD cpu, while all of qemu32, kvm64, and kvm32 use a Intel base.
Since a simple work-around exists I think the importance can be lowered.
This bug has been reported on the Ubuntu ISO testing tracker.
A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1448985
Looking through old bug tickets... can you still reproduce this issue with the latest upstream version of QEMU? Or could we close this ticket nowadays?
Since we no longer produce i386 images, this would be hard to reproduce. I could imagine the issue still exists but nobody is or will care. Essentially a difference of what features are reported via cpuid and what actually is implemented in the cpu emulation. Will close at least the Ubuntu side.
[Expired for QEMU because there has been no activity for 60 days.]
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