Framebuffer corruption in QEMU or Linux's cirrus driver

[Andy Lutomirski]

On Tue, Apr 1, 2014 at 3:09 PM, Andy Lutomirski <luto at 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