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Message-ID: <2c57be33-77b8-419b-a708-e99aa9b44395@nvidia.com>
Date: Mon, 3 Jun 2024 21:55:14 -0700
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v2 1/2] selftests/lib.mk: handle both LLVM=1 and CC=clang
 builds
To: Nathan Chancellor <nathan@kernel.org>, Mark Brown <broonie@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>,
 Muhammad Usama Anjum <usama.anjum@collabora.com>,
 Beau Belgrave <beaub@linux.microsoft.com>,
 Steven Rostedt <rostedt@goodmis.org>,
 Naresh Kamboju <naresh.kamboju@linaro.org>,
 Nick Desaulniers <ndesaulniers@google.com>,
 Justin Stitt <justinstitt@google.com>, Bill Wendling <morbo@google.com>,
 sunliming <sunliming@kylinos.cn>, Masami Hiramatsu <mhiramat@kernel.org>,
 Valentin Obst <kernel@valentinobst.de>, linux-kselftest@vger.kernel.org,
 LKML <linux-kernel@vger.kernel.org>, llvm@lists.linux.dev,
 Ryan Roberts <ryan.roberts@arm.com>
References: <20240531183751.100541-1-jhubbard@nvidia.com>
 <20240531183751.100541-2-jhubbard@nvidia.com>
 <306eebf8-bb5d-4e1a-9fa3-ad3f4ea11b9c@sirena.org.uk>
 <20240603224706.GA245774@thelio-3990X>
Content-Language: en-US
From: John Hubbard <jhubbard@nvidia.com>
In-Reply-To: <20240603224706.GA245774@thelio-3990X>
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On 6/3/24 3:47 PM, Nathan Chancellor wrote:
> On Mon, Jun 03, 2024 at 04:32:30PM +0100, Mark Brown wrote:
>> On Fri, May 31, 2024 at 11:37:50AM -0700, John Hubbard wrote:
>>> The kselftests may be built in a couple different ways:
>>>      make LLVM=1
>>>      make CC=clang
>>>
>>> In order to handle both cases, set LLVM=1 if CC=clang. That way,the rest
>>> of lib.mk, and any Makefiles that include lib.mk, can base decisions
>>> solely on whether or not LLVM is set.
>>
>> ICBW but I believe there are still some architectures with clang but not
>> lld support where there's a use case for using CC=clang.
> 
> Does CC=clang even work for the selftests? lib.mk here uses 'CC :=' so
> won't CC=clang get overridden to CC=$(CROSS_COMPILE)gcc?
> 

I received a report that someone (I forget who or what) was definitely
attempting to just set CC=clang. But yes, it definitely doesn't work
properly for CROSS_COMPILE.

And the more we talk it through, the less I like this direction that
I went off on. Let's just drop this patch and instead consider moving
kselftest builds closer to kbuild, instead of making it more different.


thanks,
-- 
John Hubbard
NVIDIA