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

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Force clean compilation with -Werror
Date: Thu, 21 May 2015 10:22:17 +0300	[thread overview]
Message-ID: <87382ql7iu.fsf@intel.com> (raw)
In-Reply-To: <1432127567-18494-1-git-send-email-chris@chris-wilson.co.uk>

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>

---

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
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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