Re: [PATCH] Makefile: Improve compressed debug info support detection

From: Arvind Sankar <nivedita@alum.mit.edu>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Fangrui Song <maskray@google.com>,
	Rong Chen <rong.a.chen@intel.com>,
	kernel test robot <lkp@intel.com>,
	kbuild-all@lists.01.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Makefile: Improve compressed debug info support detection
Date: Wed, 10 Jun 2020 19:39:54 -0400	[thread overview]
Message-ID: <20200610233954.GB2941409@rani.riverdale.lan> (raw)
In-Reply-To: <20200610233046.GA2941409@rani.riverdale.lan>

On Wed, Jun 10, 2020 at 07:30:46PM -0400, Arvind Sankar wrote:
> On Wed, Jun 10, 2020 at 02:27:55PM -0700, Nick Desaulniers wrote:
> 
> No, as-option does invoke the assembler. The problem here is that with
> -Wa, the option is only seen by the assembler, not the gcc driver. So it
> will succeed because the assembler supports it, but it will not test
> whether the gcc driver also supports it.
> 

I think in theory another way to fix it is to just use -Wa even for
CFLAGS, assuming the compiler itself doesn't have to do anything with
the option and it's purely an assembler thing. Then you'd just do the as
and ld tests.