Date: Sun, 16 May 2004 14:31:39 +0200 (CEST) From: marcov@stack.nl (Marco van de Voort) To: Marco van de Voort <marcov@stack.nl> Cc: freebsd-amd64@freebsd.org Subject: Re: ABI question, porting ports to amd64 Message-ID: <20040516123139.79BC594@toad.stack.nl> In-Reply-To: <20040515231954.4594F93@toad.stack.nl> "from Marco van de Voort at May 16, 2004 01:19:54 am"
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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.
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