Re: [Qemu-devel] [RfC PATCH 0/4] make display updates thread safe.

[Gerd Hoffmann <kraxel@redhat.com>]

  Hi,

> I've spent a bit of time over the weekend attempting to convert the
> SPARC CG3/TCX framebuffers over to use your new code and pushed the
> result to my github branch here:
> https://github.com/mcayland/qemu/commits/vga-fixes-sparc.

work/vga-fixes branch updated & rebased to latest master, with your
patches added.

> Using your current git branch, I get an assert() using VGA under
> qemu-system-ppc on startup unless I change the first assert to
> "assert(start >= snap->start)".
> 
> I'm also not convinced by the second assert "assert(start + length <
> snap->end)" either. In the example CG3/TCX conversions I ended up having
> to subtract 1 from the size of the region passed to
> memory_region_snapshot_get_dirty() in order to avoid it firing when
> accessing the last scanline which seems wrong. I didn't explicitly add a
> patch to change this to "<=" in my git patchset just in case it broke
> further assumptions in the bitmap code relating to the end address.

Both asserts should use inclusive compare.  Added a patch fixing the
other assert too.

> 2) Redraw issues with CG3/TCX after conversion
> 
> Despite the conversion from your patches looking reasonably
> straightforward, I still see problems with areas of the screen not
> updating after conversion. I can easily reproduce these locally as follows:
> 
> ./qemu-system-sparc -vga cg3 -prom-env 'auto-boot?=false'
> ./qemu-system-sparc -vga tcx -g 1024x768x8 -prom-env 'auto-boot?=false'
> ./qemu-system-sparc -vga tcx -g 1024x768x24 -prom-env 'auto-boot?=false'

Hmm, I have a blank screen only (yellow with cg3, black with tcx).
No openfirmware prompt showing up ...

> Finally on a slightly unrelated note, the TCX driver still has old code
> for 8 and 16 bpp surfaces in QEMU. Am I right in understanding that all
> surfaces in QEMU are now 32-bit and the 8/16 bpp code can be removed?

Yes, that is correct.  tcx uses qemu_resize_console() so surfaces will
always be 32bpp.

cheers,
  Gerd