From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 94EA83FE6 for ; Mon, 4 Oct 2021 19:03:36 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10127"; a="311763116" X-IronPort-AV: E=Sophos;i="5.85,346,1624345200"; d="scan'208";a="311763116" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Oct 2021 10:44:18 -0700 X-IronPort-AV: E=Sophos;i="5.85,346,1624345200"; d="scan'208";a="477275904" Received: from pmittal1-mobl.gar.corp.intel.com (HELO localhost) ([10.251.223.27]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Oct 2021 10:43:55 -0700 From: Jani Nikula To: Nathan Chancellor , Joonas Lahtinen , Rodrigo Vivi Cc: Nick Desaulniers , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Nathan Chancellor Subject: Re: [PATCH v2] drm/i915: Clean up disabled warnings In-Reply-To: <20210914194944.4004260-1-nathan@kernel.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20210914194944.4004260-1-nathan@kernel.org> Date: Mon, 04 Oct 2021 20:43:41 +0300 Message-ID: <87v92c1y9e.fsf@intel.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Tue, 14 Sep 2021, Nathan Chancellor wrote: > i915 enables a wider set of warnings with '-Wall -Wextra' then disables > several with cc-disable-warning. If an unknown flag gets added to > KBUILD_CFLAGS when building with clang, all subsequent calls to > cc-{disable-warning,option} will fail, meaning that all of these > warnings do not get disabled [1]. > > A separate series will address the root cause of the issue by not adding > these flags when building with clang [2]; however, the symptom of these > extra warnings appearing can be addressed separately by just removing > the calls to cc-disable-warning, which makes the build ever so slightly > faster because the compiler does not need to be called as much before > building. > > The following warnings are supported by GCC 4.9 and clang 10.0.1, which > are the minimum supported versions of these compilers so the call to > cc-disable-warning is not necessary. Masahiro cleaned this up for the > reset of the kernel in commit 4c8dd95a723d ("kbuild: add some extra > warning flags unconditionally"). > > * -Wmissing-field-initializers > * -Wsign-compare > * -Wtype-limits > * -Wunused-parameter > > -Wunused-but-set-variable was implemented in clang 13.0.0 and > -Wframe-address was implemented in clang 12.0.0 so the > cc-disable-warning calls are kept for these two warnings. > > Lastly, -Winitializer-overrides is clang's version of -Woverride-init, > which is disabled for the specific files that are problematic. clang > added a compatibility alias in clang 8.0.0 so -Winitializer-overrides > can be removed. > > [1]: https://lore.kernel.org/r/202108210311.CBtcgoUL-lkp@intel.com/ > [2]: https://lore.kernel.org/r/20210824022640.2170859-1-nathan@kernel.org/ > > Reviewed-by: Nick Desaulniers > Signed-off-by: Nathan Chancellor Thanks for the patch, and sorry for the delay. Exceptionally pushed to drm-intel-gt-next instead of drm-intel-next because some of the dependencies such as 43192617f781 ("drm/i915: Enable -Wsometimes-uninitialized") were queued there too. BR, Jani. > --- > > v1 -> v2: https://lore.kernel.org/r/20210824232237.2085342-1-nathan@kernel.org/ > > * Rebase on drm-intel-gt-next now that the prerequisite patch series has > been merged: https://lore.kernel.org/r/87wnnj13t5.fsf@intel.com/ > > * Add Nick's reviewed-by tag. > > drivers/gpu/drm/i915/Makefile | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile > index c584188aa15a..fd99374583d5 100644 > --- a/drivers/gpu/drm/i915/Makefile > +++ b/drivers/gpu/drm/i915/Makefile > @@ -13,13 +13,11 @@ > # will most likely get a sudden build breakage... Hopefully we will fix > # new warnings before CI updates! > subdir-ccflags-y := -Wall -Wextra > -subdir-ccflags-y += $(call cc-disable-warning, unused-parameter) > -subdir-ccflags-y += $(call cc-disable-warning, type-limits) > -subdir-ccflags-y += $(call cc-disable-warning, missing-field-initializers) > +subdir-ccflags-y += -Wno-unused-parameter > +subdir-ccflags-y += -Wno-type-limits > +subdir-ccflags-y += -Wno-missing-field-initializers > +subdir-ccflags-y += -Wno-sign-compare > subdir-ccflags-y += $(call cc-disable-warning, unused-but-set-variable) > -# clang warnings > -subdir-ccflags-y += $(call cc-disable-warning, sign-compare) > -subdir-ccflags-y += $(call cc-disable-warning, initializer-overrides) > subdir-ccflags-y += $(call cc-disable-warning, frame-address) > subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror > > > base-commit: 43192617f7816bb74584c1df06f57363afd15337 -- Jani Nikula, Intel Open Source Graphics Center