[PATCH] drm/r128: fix build for UML

[Johannes Berg]

On Wed, 2021-09-01 at 19:17 -0700, Randy Dunlap wrote:
> Fix a build error on CONFIG_UML, which does not support (provide)
> wbinvd(). UML can use the generic mb() instead.
> 
> ../drivers/gpu/drm/r128/ati_pcigart.c: In function ‘drm_ati_pcigart_init’:
> ../drivers/gpu/drm/r128/ati_pcigart.c:218:2: error: implicit declaration of function ‘wbinvd’ [-Werror=implicit-function-declaration]
>   wbinvd();
>   ^~~~~~
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") # pre-git

Arguably, that could be

Fixes: 68f5d3f3b654 ("um: add PCI over virtio emulation driver")

because prior to that, Kconfig options depending on PCI couldn't be
selected on ARCH=um.

johannes