Date: Wed, 30 Nov 2005 13:45:09 +0100
From: Andi Kleen <ak@suse.de>
To: Jari Ruusu <jariruusu@users.sourceforge.net>
Cc: Benjamin LaHaise <bcrl@kvack.org>, Andi Kleen <ak@suse.de>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/9] x86-64 put current in r10
Message-ID: <20051130124508.GK19515@wotan.suse.de>
References: <20051130042118.GA19112@kvack.org> <438D4905.9F023405@users.sourceforge.net>
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> Your patch breaks all out-of-tree amd64 assembler code used in kernel. r10
> register is one of those registers that does not need to be preserved across
> function calls, and reserving that register for other purpose means that all
> assembler code using r10 in kernel must be rewritten. This is deeply
> unfunny.

Well, the changes should be minor.

> 
> Please don't apply Ben's patch. It is already bad enough having to deal with
> two incompatible calling conventions on 32 bit x86.

43KB .text savings are hard to argue against. There is no guarantee
for a stable kernel ABI. If you maintain out of tree code you 
will need to live with the occasional changes.

-Andi
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