Re: [PATCH 1/2] drm/i915: Disable -Woverride-init

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	intel-gfx@lists.freedesktop.org, Joonas@freedesktop.org,
	Tomi Sarvela <tomi.p.sarvela@intel.com>
Subject: Re: [PATCH 1/2] drm/i915: Disable -Woverride-init
Date: Fri, 13 Oct 2017 19:47:25 +0300	[thread overview]
Message-ID: <20171013164725.GE10981@intel.com> (raw)
In-Reply-To: <20171013160830.16065-1-chris@chris-wilson.co.uk>

On Fri, Oct 13, 2017 at 05:08:29PM +0100, Chris Wilson wrote:
> We commonly use an inheritance style approach to device parameters,
> where later generations inherit the defaults from earlier generations
> and then override settings that change. For example, in i915_pci.c
> BDW_FEATURES pulls in HSW_FEATURES, makes a few changes for 48bit
> contexts and then individual Broadwell stanzas make further adjustments
> for different GT configs.
> 
> This causes a lot of warnings with make W=1 from -Woverride-init. We
> could use
> 	#pragma GCC diagnostic push
> 	#pragma GCC diagnostic ignored "-Woverride-init"
> 	...
> 	#pragma GCC diagnostic pop
> around the offenders, but the pattern is used frequently enough in the
> driver to prefer just disabling the warning entirely.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Tomi Sarvela <tomi.p.sarvela@intel.com>
> ---
>  drivers/gpu/drm/i915/Makefile | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 66d23b619db1..0bb6e423ecd7 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -2,7 +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
> +subdir-ccflags-y := -Wno-override-init # used frequently for "inheritance"

This doesn't seem to override what W=n does so not sure why we'd need it
here, unless we add more warning flags ourselves. Or does you gcc spew
these without W=1?

Looks like I can can actually do 
subdir-ccflags-y := -Wall -Wextra -Wno-unused-parameter -Wno-type-limits
		    -Wno-missing-field-initializers -Wno-override-init
without any warnings with gcc 5.4.

-Wunused-but-set-variable reveals some more (noticed those when I ran
with W=1). Most look like easy to silence. The atomic interator macros
seem to trigger this all the time however, which may not be so easy to
sort out. Not sure.

> +subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror
>  subdir-ccflags-y += \
>  	$(call as-instr,movntdqa (%eax)$(comma)%xmm0,-DCONFIG_AS_MOVNTDQA)
>  
> -- 
> 2.15.0.rc0
> 
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC
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