[PATCH] allow 32bpp framebuffers for cirrus drm

[Gerd Hoffmann]

On Mo, 2014-10-27 at 11:00 -0400, Adam Jackson wrote:
> On Fri, 2014-10-24 at 18:31 -0700, Stéphane Marchesin wrote:
> 
> > Dave, Adam: are you ok with this patch?
> 
> Seems like it doesn't go far enough?  You'd already need an "aware"
> guest to have this work, since the chip actually being emulated didn't
> have 32bpp.  The pitch check would prevent 1024x768x32 and larger from
> working, which makes it sort of a weak win on its own.
> 
> Could we read the BAR size from the device instead of hardcoding 4M?
> That alone would make 1920x1200x16 work; and then, if that pitch limit
> isn't encoded into the register space representation, the aware guest
> would have resolutions worth using at least be possible.

How about stop using cirrus and go for 'qemu -vga std' instead?

Linux kernel 3.14+ comes with a modesetting driver for the qemu standard
vga (CONFIG_DRM_BOCHS).  Just switch over, and all your cirrus pain is
gone.

That is much better than trying use features the real cirrus hardware
never had, then praying that all qemu versions in the wild are actually
doing what you want qemu do.

cheers,
  Gerd

https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/