linux-kernel - Re: Rebuilding and checksumming the Linux kernel

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Date:	Sun, 1 Apr 2007 22:03:21 -0300
From:	"Edgardo Hames" <ehames@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: Re: Rebuilding and checksumming the Linux kernel

On Apr 1, 6:10 pm, "David Schwartz"  wrote:
> > I'm working on a project with teams spread across the world and we all
> > work on the same repository patching the kernel and then integrating
> > into a common main branch. Even though we label the source code, we
> > would like to make sure that we are all building the same kernel by
> > running md5sum on the resulting binary.
> > Right now, this is not possible because the kernel includes a
> > timestamp and a build number on the binary. What are this timestamps
> > used for? Can we just remove them? Is there any other thing that may
> > lead to different binaries? (we are using the exact toolchains and
> > build machines, so we can assume that the same executable is generated
> > if the input source is the same).
>
> I think this is wrong in principle even if you can get it to work in
> practice. If you want to all work on the same kernel, then keep a single
> copy somewhere that you all work from. There is no reason the same source
> code will or should always produce the same output. Compilers are not
> generally required to be deterministic.

Could you please be a little more specific? We keep toolchains in our
SCM tool, so we can always retrieve a particular version of them and
rebuild with them. Why shouldn't we get the same binary then? I'm
really interested in hearing your opinion on this practice.

Thanks,
Ed
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