Arch Linux

cptG

Member

Registered: 2014-07-08

Posts: 7

x86_64: qemu hangs with --enable-kvm

Hello!

I'm not sure with which update this started but qemu will not start anymore as soon as --enable-kvm flag is passed.
It does not crash, it simply hangs at 100%. When I switch between (in qemu's window itself) from graphical to text console and back, it sais that the guest "has not yet initialized the display".

This happens with both:
- win7 on a dedicated lvm drive
- arch linux boot image (archlinux-2015.06.01-dual.iso)

Since I'm using an nvidia card, I tried with both nouveau and the official binary driver - no difference.

the kernel package installed is 4.2.3-1, qemu is at 2.4.0.1-1 - both x86_64 as the title suggests
The following command boots the arch image successfully:

qemu-system-x86_64 -m 4096 -boot c -vga std -hda archlinux-2015.06.01-dual.iso

The following commands leads to the hang:

qemu-system-x86_64 -enable-kvm -cpu host -smp 8,sockets=1,cores=4,threads=2 -m 4096 -boot c -vga std -hda archlinux-2015.06.01-dual.iso
qemu-system-x86_64 -enable-kvm -cpu host -smp 8,sockets=1,cores=4,threads=2 -m 4096 -boot c -vga std -hda archlinux-2015.06.01-dual.iso

The thing is: my win7 will not boot if I leave out the kvm-related options. It starts to boot, ending up in a BSOD. And that's a BSOD of the evil kind - nothing more that a line with addressess is printed

Is anyone else experiencing this?

How can I dig deeper / debug further?

Oh, I also recently cleared my package cache so a downgrade is not possible

edit oh, nothing in dmesg either - as in: no output after qemu is started

edit2:
both kvm and kvm_intel modules are loaded. rmmodding them and modprobing kvm_intel yields the following kernel message:

kvm: VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL does not work properly. Using workaround

...but according to this bug report from 2012 this message should not be a problem

Cheers,

cptG

Last edited by cptG (2015-10-14 20:22:52)

cptG

Member

Registered: 2014-07-08

Posts: 7

Re: x86_64: qemu hangs with --enable-kvm

OK, self-replying because the edits are getting ridiculous...

I just took the PKGBUILD from aur for qemu 2.4.0, changed the version number to 2.3.1 and built the package. The kvm problem is gone now but this mere version-number-switcheroo feels scary as s$%t.
Any way I can get my hands on the original PKGBUILD fro 2.3.1?

Anyway, this does not feel like a solution so I'm not yet marking as [SOLVED], I'd relly like to see if I'm the only one with this problem and maybe dig deeper into it.

cptG

R00KIE

Forum Fellow

From: Between a computer and a chair

Registered: 2008-09-14

Posts: 4,734

Re: x86_64: qemu hangs with --enable-kvm

https://wiki.archlinux.org/index.php/Arch_Linux_Archive

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R00KIE
Tm90aGluZyB0byBzZWUgaGVyZSwgbW92ZSBhbG9uZy4K

cptG

Member

Registered: 2014-07-08

Posts: 7

Re: x86_64: qemu hangs with --enable-kvm

Cool, thanks! I'll check it out ASAP.

Lone_Wolf

Member

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 11,911

Re: x86_64: qemu hangs with --enable-kvm

cptG , recently there have been many reports of qemu + intel cpu + kernel 4.2.x giving problems.

Most people downgraded kernel or qemu, but atleast 1 person has found  a workaround that doesn't require downgrading :
https://bbs.archlinux.org/viewtopic.php?id=203548

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Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

(A works at time B)  && (time C > time B ) ≠  (A works at time C)

cptG

Member

Registered: 2014-07-08

Posts: 7

Re: x86_64: qemu hangs with --enable-kvm

Ah, that sounds like exactly my problem. Thanks, Lone_Wolf!