linux-kernel - Re: register long sp asm("r1") incorrect

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Message-ID: <4B79C775.1050903@zytor.com>
Date:	Mon, 15 Feb 2010 14:15:17 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	Pavel Machek <pavel@....cz>, paulus@...ba.org,
	linuxppc-dev@...abs.org,
	kernel list <linux-kernel@...r.kernel.org>,
	Segher Boessenkool <segher@...nel.crashing.org>,
	bergner@...t.ibm.com
Subject: Re: register long sp asm("r1") incorrect

On 02/15/2010 01:04 PM, Benjamin Herrenschmidt wrote:
> 
> It's true that most other use of it we have are global scope (local_paca
> in r13, glibc use of r2/r13, etc...) afaik, but since r1 itself is the
> stack pointer always, I think they pretty much guarantee it works.
> 

It should work, because r1, being the stack pointer, is already marked a
reserved register in gcc.

The reference Pavel is citing bascially states that gcc won't globally
reserve the register, which is true, but it is already reserved anyway.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.
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