Re: [PATCH] drm/i915: Force clean compilation with -Werror

From: Daniel Vetter <daniel@ffwll.ch>
To: Jani Nikula <jani.nikula@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Force clean compilation with -Werror
Date: Thu, 21 May 2015 11:38:03 +0200	[thread overview]
Message-ID: <20150521093803.GR15256@phenom.ffwll.local> (raw)
In-Reply-To: <87382ql7iu.fsf@intel.com>

On Thu, May 21, 2015 at 10:22:17AM +0300, Jani Nikula wrote:
> On Wed, 20 May 2015, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> > Our driver compiles clean (nowadays thanks to 0day) but for me, at least,
> > it would be beneficial if the compiler threw an error rather than a
> > warning when it found a piece of suspect code. (I use this to
> > compile-check patch series and want to break on the first compiler error
> > in order to fix the patch.)
> >
> > v2: Kick off a new "Debugging" submenu for i915.ko
> >
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > ---
> >  drivers/gpu/drm/i915/Kconfig       | 8 ++++++++
> >  drivers/gpu/drm/i915/Kconfig.debug | 5 +++++
> >  drivers/gpu/drm/i915/Makefile      | 2 ++
> >  3 files changed, 15 insertions(+)
> >  create mode 100644 drivers/gpu/drm/i915/Kconfig.debug
> >
> > diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
> > index 74acca9bcd9d..76c425ca2a2c 100644
> > --- a/drivers/gpu/drm/i915/Kconfig
> > +++ b/drivers/gpu/drm/i915/Kconfig
> > @@ -71,3 +71,11 @@ config DRM_I915_PRELIMINARY_HW_SUPPORT
> >  	  option changes the default for that module option.
> >  
> >  	  If in doubt, say "N".
> > +
> > +menu "Debugging"
> > +
> > +depends on DRM_I915
> > +
> > +source drivers/gpu/drm/i915/Kconfig.debug
> > +
> > +endmenu
> > diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
> > new file mode 100644
> > index 000000000000..070a03527bc5
> > --- /dev/null
> > +++ b/drivers/gpu/drm/i915/Kconfig.debug
> > @@ -0,0 +1,5 @@
> > +config DRM_I915_WERROR
> > +	bool "Force GCC to throw an error instead of a warning when compiling"
> > +	default n
> > +	---help---
> > +	  Add -Werror to the build flags for (and only for) i915.ko
> > diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> > index b7ddf48e1d75..93d99b744531 100644
> > --- a/drivers/gpu/drm/i915/Makefile
> > +++ b/drivers/gpu/drm/i915/Makefile
> > @@ -2,6 +2,8 @@
> >  # Makefile for the drm device driver.  This driver provides support for the
> >  # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
> >  
> > +subdir-ccflags-$(CONFIG_DRM_I915_WERROR) := -Werror
> 
> arch/powerpc seems to have a similar thing.
> 
> Acked-by: Jani Nikula <jani.nikula@intel.com>

Ok let's give this a shot and see what happens. Queued for -next, thanks
for the patch.
-Daniel
> 
> ---
> 
> I see that we're clean also with
> 
>   -Wall -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wno-override-init
> 
> so could have those with e.g. subdir-ccflags-$(CONFIG_DRM_I915_WEXTRA).
> 
> I might argue we could and should get rid of
> -Wno-missing-field-initializers -Wno-override-init too...
> 
> BR,
> Jani.
> 
> 
> 
> 
> > +
> >  # Please keep these build lists sorted!
> >  
> >  # core driver code
> > -- 
> > 2.1.4
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

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