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In-Reply-To: <20040515231954.4594F93@toad.stack.nl> "from Marco van de Voort
 at May 16, 2004 01:19:54 am"
To: Marco van de Voort <marcov@stack.nl>
Date: Sun, 16 May 2004 14:31:39 +0200 (CEST)
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From: marcov@stack.nl (Marco van de Voort)
cc: freebsd-amd64@freebsd.org
Subject: Re: ABI question, porting ports to amd64
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> I read the ABI info on x86-64.org, and objdumped some linux and freebsd
> code, and I ran into a linux<->freebsd difference something I can't figure
> out:

Answering my own question:

FreeBSD uses the gcc mechanism to build the same parameterlist for a syscall
like for a normal procedure. (to avoid having to shift params)

The register for the 4th parameter for gcc is %rcx, for the kernel it is
%r10. So gcc puts the 4th param in %rcx, and the move moves it to %r10 for
the kernel.