BUG / design challenge: vmwgfx + PRIME handle free == clobbering errno

[Zack Rusin]

On Tue, Jan 9, 2024 at 11:06 AM Xaver Hugl <xaver.hugl at kde.org> wrote:
>
> Hi,
>
> KWin does use DRM_CLIENT_CAP_CURSOR_PLANE_HOTSPOT.

Can you point me to the code that implements it? Just wanted to take a
quick look, because I didn't see the cursor on KDE 6 after fixing the
kernel oops.

> Tying the check to
> DRM_CLIENT_CAP_ATOMIC instead would IMO make more sense though (even if it's
> still weird) and would work with older versions of KWin and other compositors.

Unfortunately xf86-video-modesetting advertises CLIENT_CAP_ATOMIC and
uses GL where our GL driver assumes the prime object is not GEM. Not
impossible, as mentioned before, we can always add code to the kernel
that handles both but I don't think there's any particularly clean
solutions here. We'll probably play with a few solutions and see which
one is the cleanest.

z