Date: Tue, 23 Sep 2008 07:56:11 -0700 From: Sam Leffler <sam@freebsd.org> To: "David E. O'Brien" <obrien@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/conf files src/sys/fs/tmpfs tmpfs.h tmpfs_subr.c tmpfs_vnops.c src/sys/i386/i386 bios.c src/sys/ia64/ia64 efi.c sal.c src/sys/libkern memcmp.c src/sys/mips/mips support.S src/sys/sys libkern.h Message-ID: <48D9038B.3040000@freebsd.org> In-Reply-To: <200809231446.m8NEkQev007507@repoman.freebsd.org> References: <200809231446.m8NEkQev007507@repoman.freebsd.org>
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David E. O'Brien wrote:
> obrien 2008-09-23 14:45:10 UTC
>
> FreeBSD src repository
>
> Modified files:
> sys/conf files
> sys/fs/tmpfs tmpfs.h tmpfs_subr.c tmpfs_vnops.c
> sys/i386/i386 bios.c
> sys/ia64/ia64 efi.c sal.c
> sys/mips/mips support.S
> sys/sys libkern.h
> Added files:
> sys/libkern memcmp.c
> Log:
> SVN rev 183299 on 2008-09-23 14:45:10Z by obrien
>
> The kernel implemented 'memcmp' is an alias for 'bcmp'. However, memcmp
> and bcmp are not the same thing. 'man bcmp' states that the return is
> "non-zero" if the two byte strings are not identical. Where as,
> 'man memcmp' states that the return is the "difference between the
> first two differing bytes (treated as unsigned char values" if the
> two byte strings are not identical.
>
> So provide a proper memcmp(9), but it is a C implementation not a tuned
> assembly implementation. Therefore bcmp(9) should be preferred over memcmp(9).
>
>
Given the performance difference this change should have been reviewed
before dumping it into the tree. I do not agree with this; did you post
it somewhere?
Sam
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