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

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Date:   Mon, 26 Jun 2017 16:54:17 +0000
From:   Nick Terrell <terrelln@...com>
To:     "dsterba@...e.cz" <dsterba@...e.cz>,
        Adam Borowski <kilobyte@...band.pl>
CC:     Kernel Team <Kernel-team@...com>, Chris Mason <clm@...com>,
        Yann Collet <cyan@...com>,
        "squashfs-devel@...ts.sourceforge.net" 
        <squashfs-devel@...ts.sourceforge.net>,
        "linux-btrfs@...r.kernel.org" <linux-btrfs@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/4] btrfs: Add zstd support

Thanks for the clarification! I will fix the divisions.

On 6/26/17, 5:12 AM, "David Sterba" <dsterba@...e.cz> wrote:

    On Sun, Jun 25, 2017 at 11:30:22PM +0200, Adam Borowski wrote:
    > 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.
    
    No do_div please, div_u64 or div64_u64.