Re: [PATCH] [v2] amdgpu: fix gcc-4.8 build warnings

From: Arnd Bergmann <arnd@arndb.de>
To: "Kazlauskas, Nicholas" <nicholas.kazlauskas@amd.com>
Cc: "Harry Wentland" <harry.wentland@amd.com>,
	"Leo Li" <sunpeng.li@amd.com>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	"Christian König" <christian.koenig@amd.com>,
	"David (ChunMing) Zhou" <David1.Zhou@amd.com>,
	"David Airlie" <airlied@linux.ie>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Rodrigo Siqueira" <Rodrigo.Siqueira@amd.com>,
	"Bhawanpreet Lakha" <Bhawanpreet.Lakha@amd.com>,
	"amd-gfx list" <amd-gfx@lists.freedesktop.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] [v2] amdgpu: fix gcc-4.8 build warnings
Date: Wed, 29 Apr 2020 22:16:10 +0200	[thread overview]
Message-ID: <CAK8P3a3YCKtkt2pHQZGg8SQsbdA2Ai3ZhxCGKToD2KVRHQgnrw@mail.gmail.com> (raw)
In-Reply-To: <f9738a59-5c7d-57ad-0d56-6455d6938964@amd.com>

On Wed, Apr 29, 2020 at 3:42 PM Kazlauskas, Nicholas
<nicholas.kazlauskas@amd.com> wrote:
>
> On 2020-04-29 5:20 a.m., Arnd Bergmann wrote:
> > Older compilers warn about initializers with incorrect curly
> > braces:
> >
> > drivers/gpu/drm/drm_dp_mst_topology.c: In function 'drm_dp_mst_dsc_aux_for_port':
> > drivers/gpu/drm/drm_dp_mst_topology.c:5497:9: error: missing braces around initializer [-Werror=missing-braces]
> >    struct drm_dp_desc desc = { 0 };
> >           ^
> >
> > Change all instances in the amd gpu driver to using the GNU empty
> > initializer extension.
>
> These should actually be memset - instead of GCC complaining, it'll be
> clang instead.

I'm not sure what you mean, clang certainly supports most GNU extensions,
and this one is used all over the kernel.

There is a good reason for using memset instead of ={}, e.g. when you want
to be sure that all padding fields get initialized before copying
stack variables
to user space, but I find it a little harder to read.

       Arnd