Fwd: Re: kvm-31 seg fault

[Chris Clayton <chris2553-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>]

Forgot to cc this to the list, sorry
----------  Forwarded Message  ----------

Subject: Re: [kvm-devel] kvm-31 seg fault
Date: Tuesday 24 July 2007
From: Chris Clayton <chris2553-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
To: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Hi again Avi,

On Sunday 22 July 2007, you wrote:
> Chris Clayton wrote:
> > On Sunday 22 July 2007, you wrote:
> >> Chris Clayton wrote:
> >>> Hi,
> >>>
> >>> I'm getting a seg fault running kvm-31 on linux-2.6.22.1-cfs-v19 and
> >>> linux-2.6.22-git17.
> >>>
> >>> If I use the kvm-31 kernel modules with qemu from kvm-29, all is OK
> >>> Also, running "non-kvm" guests, such as Windows ME, works fine with
> >>> kvm-31.
> >>>
> >>> I have an strace log but its over 99 Kilobytes, so I haven't attached
> >>> it to this mail. More than happy to compress it and send it by private
> >>> mail, if required.
> >>>
> >>> I'm not subscribed, so please cc me.
> >>
> >> Please send it to me.  What guest are you running?  Is the host 32-bit
> >> or 64-bit?
> >
> > Attached is the log from 2.6.22-git17
> >
> > The host is 32bit and the guest is freebsd-6.2 although I get the same
> > seg fault with slackware 10.2 and damn small linux 3.1 (all 32 bit).
>
> Unfortunately that doesn't help.  Can you generate a core ('ulimit -c
> unlimited' may help) and get a stacktrace from gdb?

I've been doing some more digging around here and thought I'd report my 
findings. I've found that under kvm 31 and 33, qemu-system-x86_64 always 
fails with a seg fault when the (__thread) variable vcpu_env (declared at 
line 33 of qemu-kvm.c) is accessed in kvm_update_interrupt_request(). I've 
inserted useless statements (printf()s and assignments) at the head of the 
function, and always get the seg fault at the first access to the variable.

I'm building qemu with gcc-3.4.6, but to eliminate a fault in that compiler, 
I've also built the application on my laptop with gcc-3.3.6 and copied the 
binary over to my desktop machine. I still get the seg fault.

Sorry if this is just noise on your line, but I thought I'd send it just in 
case it's useful.

Chris

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