[PATCH xserver 0/3] Use DRM GetFB2 ioctl

[Daniel Stone]

Hi,
This short patchset makes modesetting use the shiny, new, and completely
not at all merged GetFB2 DRM ioctl:
https://lists.freedesktop.org/archives/dri-devel/2018-March/170512.html

When starting Xorg with -background none, it uses GetFB to interrogate
the current framebuffer, importing it into a Glamor texture so it can
copy back to its own storage. Unfortunately, if your buffer was
multi-planar (e.g. new Intel with auxiliary compression buffer), or just
too exotic to be described without a modifier (etnaviv in tiled mode),
GetFB fell short of what we actually needed.

GetFB2 is the equivalent to AddFB2 (or AddFB2WithModifiers; both the
same from an ioctl point of view), so this ports modesetting to use that
where available and use with more complex buffers.

The kernel ABI rules require positive review from real userspace (not
random hacked-up libdrm tests) before merging. Given that, I'd
appreciate someone taking a look at the use of GetFB2 here, and
following up with a statement that they think the ABI is actually good
and long-term usable for what Xorg needs. (Or, well, some kind of
constructive criticism.)

Happy new-kernel-ABI Friday!

Cheers,
Daniel