[Qemu-devel] Framebuffer corruption in QEMU or Linux's cirrus driver

[Qemu-devel] Framebuffer corruption in QEMU or Linux's cirrus driver

[Andy Lutomirski]

Running:

./virtme-run --installed-kernel

from this virtme commit:

https://git.kernel.org/cgit/utils/kernel/virtme/virtme.git/commit/?id=2b409a086d15b7a878c7d5204b1f44a6564a341f

results in a bunch of missing lines of text once bootup finishes.
Pressing enter a few times gradually fixes it.

I don't know whether this is a qemu bug or a Linux bug.

I'm seeing this on Fedora's 3.13.7 kernel and on a fairly recent
3.14-rc kernel.  For the latter, cirrus is built-in (not a module),
I'm running:

virtme-run --kimg arch/x86/boot/bzImage

and I see more profound corruption.

--Andy

Re: [Qemu-devel] Framebuffer corruption in QEMU or Linux's cirrus driver

[Andy Lutomirski]

On Tue, Apr 1, 2014 at 3:09 PM, Andy Lutomirski <luto@amacapital.net> wrote:
> Running:
>
> ./virtme-run --installed-kernel
>
> from this virtme commit:
>
> https://git.kernel.org/cgit/utils/kernel/virtme/virtme.git/commit/?id=2b409a086d15b7a878c7d5204b1f44a6564a341f
>
> results in a bunch of missing lines of text once bootup finishes.
> Pressing enter a few times gradually fixes it.
>
> I don't know whether this is a qemu bug or a Linux bug.
>
> I'm seeing this on Fedora's 3.13.7 kernel and on a fairly recent
> 3.14-rc kernel.  For the latter, cirrus is built-in (not a module),
> I'm running:
>
> virtme-run --kimg arch/x86/boot/bzImage
>
> and I see more profound corruption.

I'm guessing this is a cirrus drm bug.  bochs-drm (using virtme-run
--installed-kernel --qemu-opts -vga std) does not appear to have the
same issue.  Neither does qxl.

(qxl is painfully slow, though, and it doesn't seem to be using UC memory.)

--Andy

Re: Framebuffer corruption in QEMU or Linux's cirrus driver

[Andy Lutomirski]

On Tue, Apr 1, 2014 at 3:09 PM, Andy Lutomirski <luto@amacapital.net> wrote:
> Running:
>
> ./virtme-run --installed-kernel
>
> from this virtme commit:
>
> https://git.kernel.org/cgit/utils/kernel/virtme/virtme.git/commit/?id=2b409a086d15b7a878c7d5204b1f44a6564a341f
>
> results in a bunch of missing lines of text once bootup finishes.
> Pressing enter a few times gradually fixes it.
>
> I don't know whether this is a qemu bug or a Linux bug.
>
> I'm seeing this on Fedora's 3.13.7 kernel and on a fairly recent
> 3.14-rc kernel.  For the latter, cirrus is built-in (not a module),
> I'm running:
>
> virtme-run --kimg arch/x86/boot/bzImage
>
> and I see more profound corruption.

I'm guessing this is a cirrus drm bug.  bochs-drm (using virtme-run
--installed-kernel --qemu-opts -vga std) does not appear to have the
same issue.  Neither does qxl.

(qxl is painfully slow, though, and it doesn't seem to be using UC memory.)

--Andy

Re: [Qemu-devel] Framebuffer corruption in QEMU or Linux's cirrus driver

[Laszlo Ersek]

On 04/02/14 00:09, Andy Lutomirski wrote:
> Running:
> 
> ./virtme-run --installed-kernel
> 
> from this virtme commit:
> 
> https://git.kernel.org/cgit/utils/kernel/virtme/virtme.git/commit/?id=2b409a086d15b7a878c7d5204b1f44a6564a341f
> 
> results in a bunch of missing lines of text once bootup finishes.
> Pressing enter a few times gradually fixes it.
> 
> I don't know whether this is a qemu bug or a Linux bug.
> 
> I'm seeing this on Fedora's 3.13.7 kernel and on a fairly recent
> 3.14-rc kernel.  For the latter, cirrus is built-in (not a module),
> I'm running:
> 
> virtme-run --kimg arch/x86/boot/bzImage
> 
> and I see more profound corruption.

I'm seeing this on:
- qemu: qemu-kvm-1.5.3-55.el7.x86_64
- guest: 3.13.6-100.fc19.x86_64

Screenshots: http://people.redhat.com/~lersek/cirrusdrmfb/

Thanks
Laszlo