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List:       gentoo-dev
Subject:    Re: [gentoo-dev] Re: Re: Downgrading glibc?
From:       James Cloos <cloos () jhcloos ! com>
Date:       2011-02-16 22:39:57
Message-ID: m3d3mry562.fsf () jhcloos ! com
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>>>>> "MH" == Michael Haubenwallner <haubi@gentoo.org> writes:

MH> I've heard a colleague of mine debugged for 50(!) hours after moving
MH> some quite old application to some recent Linux before he replaced a
MH> memcpy by memmove, so this did ring some bells.

MH> However, now he said this was on Ubuntu 10.04.1 LTS, having
MH> glibc-2.11, so this might have been unrelated indeed.

Check the archives of the glibc lists, as well as its bug db.

There has been quite a bit of discussion there on that issue.

It was added for sse3 some time ago; I beleive it was Intel engineers
who contributed it for sse3, showing that it was inedeed faster on their
chips to start at the high point and decrement the counter rather than
starting at the low point and incrementing.

The discussion in their lists does a better job of documenting the issue.

-JimC
-- 
James Cloos <cloos@jhcloos.com>         OpenPGP: 1024D/ED7DAEA6

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