linux-kernel - Re: [PATCH 3/4] btrfs: Add zstd support

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Date:   Sun, 25 Jun 2017 23:30:22 +0200
From:   Adam Borowski <kilobyte@...band.pl>
To:     Nick Terrell <terrelln@...com>
Cc:     kernel-team@...com, Chris Mason <clm@...com>,
        Yann Collet <cyan@...com>,
        squashfs-devel@...ts.sourceforge.net, linux-btrfs@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] btrfs: Add zstd support

On Mon, Jun 26, 2017 at 03:03:17AM +0800, kbuild test robot wrote:
> Hi Nick,
> 
> url:    https://github.com/0day-ci/linux/commits/Nick-Terrell/lib-Add-xxhash-module/20170625-214344
> config: i386-allmodconfig (attached as .config)
> compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=i386 
> 
> All errors (new ones prefixed by >>):
> 
> >> ERROR: "__udivdi3" [lib/zstd/zstd_compress.ko] undefined!
>    ERROR: "__udivdi3" [fs/ufs/ufs.ko] undefined!

Just to save you time to figure it out:
for division when one or both arguments are longer than the architecture's
word, gcc uses helper functions that are included when compiling in a hosted
environment -- but not in freestanding.

Thus, you want do_div() instead of /; do check widths and signedness of
arguments.


Meow!
-- 
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