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Date: Sun, 14 Nov 2010 21:32:16 +0100
From: Dimitry Andric <dim@FreeBSD.org>
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To: Erik Cederstrand <erik@cederstrand.dk>
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Cc: Giorgos Keramidas <keramida@ceid.upatras.gr>,
	=?ISO-8859-1?Q?Sp=F6rlein?= <uqs@spoerlein.net>,
	FreeBSD Hackers <hackers@freebsd.org>, =?ISO-8859-1?Q?Ulrich_?=
Subject: Re: Deterministic builds?
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On 2010-11-14 21:22, Erik Cederstrand wrote:
> I'm curious as to why this might be useful? Would the mtime of the
> file not be be sufficient? I can only think of debugging purposes, but
> apart from the timestamp, two kernels with the same rev. would be
> bitwise identical,

This does not have to be the case.  For example, if you have have local
modifications, or use different settings in make.conf or src.conf.

Similarly, the host on which something is built can be interesting
metadata, because not all hosts are equal.


> If it is useful, why not brand all binaries with a rev. number and a timestamp?

There are compilers that automatically brand every binary with a "built
on" timestamp.  If you want to 'compare' such binaries, you simply need
a tool that disregards the timestamps.