Hello Geert,

On 11/16/21 10:43, Geert Uytterhoeven wrote:

[snip]

quoted

So this is already a fragile solution and $SUBJECT doesn't make things worse
IMO. Since not having something like this can lead to issues as reported by:

https://lore.kernel.org/all/20211110200253.rfudkt3edbd3nsyj@lahvuun/ (local)

We could probably do some smarter here by providing a function that checks
if the registered fbdev drivers matches the aperture base. But I'm unsure
if that's worth it. After all, fbdev drivers are likely to be disabled by
most distros soon now that we have the simpledrm driver.

Checking the aperture base is what was done in all other cases of
preventing generic (fbdev) drivers from stepping on specific drivers'
toes...

Ok, I can re-spin the patch checking if the aperture ranges overlap. There's
an apertures_overlap() function in drivers/video/fbdev/core/fbmem.c that can
be exported for fbdev drivers to use.

Another option is to just say that DRM drivers should be built as a module if
the {efi,simple}fb driver are built-in.

Best regards,
-- 
Javier Martinez Canillas
Linux Engineering
Red Hat