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Date:   Fri, 18 Jun 2021 10:42:30 +0200
From:   Heiko Carstens <hca@linux.ibm.com>
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
        linux-s390@vger.kernel.org, linux-next@vger.kernel.org,
        lkft-triage@lists.linaro.org, Arnd Bergmann <arnd@arndb.de>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Naresh Kamboju <naresh.kamboju@linaro.org>
Subject: Re: [PATCH] scripts/min-tool-version.sh: Raise minimum clang version
 to 13.0.0 for s390
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References: <YMtib5hKVyNknZt3@osiris>
 <20210617193139.856957-1-nathan@kernel.org>
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On Thu, Jun 17, 2021 at 12:31:40PM -0700, Nathan Chancellor wrote:
> clang versions prior to the current development version of 13.0.0 cannot
> compile s390 after commit 3abbdfde5a65 ("s390/bitops: use register pair
> instead of register asm") and the s390 maintainers do not intend to work
> around this in the kernel. Codify this in scripts/min-tool-version.sh
> similar to arm64 with GCC 5.1.0 so that there are no reports of broken
> builds.
> 
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> 
> This should probably go through the s390 tree with Masahiro's ack.

Thank's a lot!

I'll add the below text to the commit message, and apply it internally
first:

[hca@linux.ibm.com: breaking compatibility with older clang compilers
 is intended to finally make use of a feature which allows the
 compiler to allocate even/odd register pairs. This is possible since
 a very long time with gcc, but only since llvm-project commit
 d058262b1471 ("[SystemZ] Support i128 inline asm operands.") with
 clang. Using that feature allows to get rid of error prone register
 asm statements, of which the above named kernel commit is only the
 first of a larger not yet complete series]