Subject: Re: want to clarify powerpc assembly conventions in head.S
	and	entry.S
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Chris Friesen <cfriesen@nortelnetworks.com>
Cc: linuxppc-dev list <linuxppc-dev@lists.linuxppc.org>,
       Linux Kernel list <linux-kernel@vger.kernel.org>
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Date: Sun, 11 Apr 2004 15:25:51 +1000
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> You knew this was coming...  What's special about syscalls?  There's the 
> r3 thing, but other than that...

The whole codepath is a bit different, there's the syscall trace,
we can avoid saving much more registers are syscalls are function
calls and so can clobber the non volatiles, etc...

> Thanks for your help with this stuff.  As I've been slowly wrapping my 
> head around it I've been continuously wishing for some kind of design 
> rules document describing the various paths through the assembly code, 
> along with register conventions and such.  I eventually did find the 
> conventions linked off the penguinppc website, but it was not obvious 
> from just reading the code or the ppc stuff in the Documentation directory.
> 
> Chris
-- 
Benjamin Herrenschmidt <benh@kernel.crashing.org>

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