[PATCH] drm/i915: Autoselect CONFIG_CHECKPOINT_RESTORE for SYS_kcmp

[Daniel Vetter]

On Fri, Feb 05, 2021 at 01:03:07PM +0000, Chris Wilson wrote:
> gallium (iris) depends on os_same_file_description() to disambiguate
> screens and so avoid importing the same screen fd twice as two distinct
> entities (that share all the kernel resources, so actions on screen
> affect the other and would cause random faiure). As they depend on it,
> so must we. os_same_file_description() uses SYS_kcmp to check the file
> tables for the equivalent struct file, but SYS_kcmp is hidden behind
> CONFIG_CHECKPOINT_RESTORE. As this is not default, we must select it for
> ourselves to ensure that our userspace is fully supported.
> 
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/3046
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>

Hm shouldn't we crank this up to CONFIG_DRM?

Or embedded folks going to be unhappy about that? If so I guess we'd need
to pull out just the SYS_kcmp part ...

Asking because I think Bas is also looking at this, and it's not great if
we're building on this and then users end up with very subtly broken gl/vk
stacks :-/
-Daniel

> ---
>  drivers/gpu/drm/i915/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
> index 1e1cb245fca7..470a5214bd33 100644
> --- a/drivers/gpu/drm/i915/Kconfig
> +++ b/drivers/gpu/drm/i915/Kconfig
> @@ -21,6 +21,7 @@ config DRM_I915
>  	select ACPI_VIDEO if ACPI
>  	select ACPI_BUTTON if ACPI
>  	select SYNC_FILE
> +	select CHECKPOINT_RESTORE # gallium depends on SYS_kcmp
>  	select IOSF_MBI
>  	select CRC32
>  	select SND_HDA_I915 if SND_HDA_CORE
> -- 
> 2.20.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch