[PATCH xserver 0/5] Remove (most) 24bpp support

[Adam Jackson]

On Thu, 2016-12-08 at 09:19 -0800, Keith Packard wrote:
> > Adam Jackson <ajax at redhat.com> writes:
> > Assuming those bugs are gone, the only configurations that would break
> > are the two drivers mentioned in the commit message, and any manual
> > configuration that had set 24bpp in order to fit in available VRAM.
> 
> At a minimum, forcing those to 16bpp would at least keep the screen lit
> up.

It would, but xfree86 isn't set up to do that. The driver tells xfree86
which depth/bpp it will use, then validates modes. Worse, the check
about whether to fail because there are no modes is in the driver, so
the best the server could do is notice that PreInit failed and retry at
16bpp, which seems... icky.

> > first two we can easily fix in code, the second is a little rougher.
> > Personally, given how antique 24bpp-supporting hardware is at this
> > point, I'm okay with just a release note saying that some
> > configurations might break.
> 
> I thought there were a pile of 24bpp chips in recent server boxes?

Said devices have KMS drivers so modesetting gets this right already.
Though the "antique" comment still kind of applies, the G200 core is
old enough to vote, and the emulated cirrus in qemu is at least two
years older than that.

- ajax