Re: [PATCH] drm/i915: Autoselect CONFIG_CHECKPOINT_RESTORE for SYS_kcmp

From: Daniel Vetter <daniel@ffwll.ch>
To: Chris Wilson <chris@chris-wilson.co.uk>, Dave Airlie <airlied@gmail.com>
Cc: Jani Nikula <jani.nikula@intel.com>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Autoselect CONFIG_CHECKPOINT_RESTORE for SYS_kcmp
Date: Fri, 5 Feb 2021 16:59:12 +0100	[thread overview]
Message-ID: <YB1rUCQoa+wCEh1o@phenom.ffwll.local> (raw)
In-Reply-To: <YB1rKLGvpnFDom11@phenom.ffwll.local>

On Fri, Feb 05, 2021 at 04:58:32PM +0100, Daniel Vetter wrote:
> 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@chris-wilson.co.uk>
> > Cc: Jani Nikula <jani.nikula@intel.com>
> > Cc: Daniel Vetter <daniel.vetter@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 :-/

Forgot to add Airlie.
-Daniel

> -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

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