Re: Frame buffer corruptions with KVM >= 2.6.36

Takuya Yoshikawa
2010-10-18T12:12:21Z

(2010/10/15 15:41), Takuya Yoshikawa wrote:
> (2010/10/14 21:38), Avi Kivity wrote:
>> On 10/14/2010 02:36 PM, Jan Kiszka wrote:
>>> >
>>> >> and this commit just makes the
>>> >> corruptions more likely. This may even be a QEMU issue in the cirrus/vga
>>> >> model (both qemu-kvm and upstream show the effect).
>>> >>
>>> >
>>> > What about -no-kvm?
>>>
>>> Just booted it (took ages), and the result was actually a completely
>>> black screen. Kind of persistent corruption. This really looks like a
>>> qemu issue now, maybe even a regression as I don't remember running into
>>> such effects a while back.
>>
>> Worked fine for me (though yes it was slow - did tcg regress?).
>>
>
> I reread my commit but could not find any reason to make this corruption
> in kernel side.
>
> But at least, I want to make it clear whether my commit was just a magnifier
> of this problem, I know that magnifier itself is bad, or not.
>
> Though I'm now trying some debugging but have not got a way to show
> kvm_vm_ioctl_get_dirty_log() is 100% correct yet.
>

I tried some tests and found another issue.

I opened a terminal in one workspace and did "find /" on it. Then I switched
to another workspace. When I switched back to the first one, the display of
"find /" result was frozen.

I also replaced kvm_vm_ioctl_get_dirty_log() with the version before my patch was
applied and got the same result.

I don't know this is related to your report, but something seems wrong.

Thanks,
Takuya