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Date:   Thu, 29 Jul 2021 16:42:53 +0200
From:   Heiko Carstens <hca@linux.ibm.com>
To:     Vasily Gorbik <gor@linux.ibm.com>
Cc:     Dimitri John Ledkov <dimitri.ledkov@canonical.com>,
        kbuild-all@lists.01.org, linux-kernel@vger.kernel.org,
        kernel test robot <lkp@intel.com>
Subject: Re: [PATCH] s390/boot: fix zstd build for -march=z900
Message-ID: <YQK+bbDzoqhOngxZ@osiris>
References: <202107280146.D9p1EaKo-lkp@intel.com>
 <cover.thread-f0f589.your-ad-here.call-01627564869-ext-2765@work.hours>
 <patch-1.thread-f0f589.git-f0f58936888f.your-ad-here.call-01627564869-ext-2765@work.hours>
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On Thu, Jul 29, 2021 at 03:29:19PM +0200, Vasily Gorbik wrote:
> zstd decompression uses __builtin_clz() which fails back to __clzdi2()
> when the kernel is built for older hardware like z900. This leads to
> build failures like the following:
> s390x-11.1.0-ld: /devel/src/kernel/arch/s390/boot/compressed/../../../../lib/zstd/bitstream.h:148: undefined reference to `__clzdi2'
> 
> Fix that by optionally including lib/clz_ctz.c into the decompressor.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Fixes: 7b034d9c1b08 ("s390/boot: add zstd support")
> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
> ---
>  arch/s390/boot/compressed/Makefile  | 1 +
>  arch/s390/boot/compressed/clz_ctz.c | 2 ++
>  2 files changed, 3 insertions(+)
>  create mode 100644 arch/s390/boot/compressed/clz_ctz.c

Applied, thanks!