Quoting Ville Syrjälä (2025-12-16 23:38:53) > On Tue, Dec 16, 2025 at 01:35:12PM +0200, Joonas Lahtinen wrote: > > Building the driver without CONFIG_X86_PAT would yield in reduced > > platform/uAPI support and is not currently planned to be supported. > > > > Add a dependency in Kconfig to avoid issues with such build until > > somebody steps up to fix and validate such builds. > > The driver works just fine w/o PAT on older GPUs at least.
Wouldn't this fall under the reduced platform support clause? Would you like me to rephrase the above wording to be more clear? The other option would be to identify all such platforms and only probe driver for those at runtime if kernel was built with X86_PAT=n. Patches welcome :) > Otherwise > it wouldn't work at all on any P3 class CPU as the kernel completely > disables PAT support on those even if the kernel is built with > X86_PAT=y. That's interesting, thanks for sharing. I guess that would be exactly to avoid having to support kernel builds with X86_PAT=n? At least the impact of limited functionality is clearly limited to set of the older platforms which never had the functionality to begin with even if we added new uAPI so that shouldn't be a problem with diverging uAPI based on compile time config. Regards, Joonas > You can also disable PAT on the command line with "nopat". > > > > > Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15410 > > Signed-off-by: Joonas Lahtinen <[email protected]> > > Reported-by: Norbert Lange <[email protected]> > > Cc: Jani Nikula <[email protected]> > > Cc: Tvrtko Ursulin <[email protected]> > > Cc: Rodrigo Vivi <[email protected]> > > --- > > drivers/gpu/drm/i915/Kconfig | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig > > index 5e939004b6463..a19a233239056 100644 > > --- a/drivers/gpu/drm/i915/Kconfig > > +++ b/drivers/gpu/drm/i915/Kconfig > > @@ -2,7 +2,7 @@ > > config DRM_I915 > > tristate "Intel 8xx/9xx/G3x/G4x/HD Graphics" > > depends on DRM > > - depends on X86 && PCI > > + depends on X86 && X86_PAT && PCI > > depends on !PREEMPT_RT > > select INTEL_GTT if X86 > > select INTERVAL_TREE > > -- > > 2.52.0 > > -- > Ville Syrjälä > Intel
