From: Segher Boessenkool <segher@kernel.crashing.org>
To: Kumar Gala <kumar.gala@freescale.com>
Cc: ppc64-dev <linuxppc64-dev@ozlabs.org>,
linuxppc-dev list <linuxppc-dev@ozlabs.org>
Subject: Re: r13 is non-volatile?
Date: Thu, 8 Sep 2005 19:01:18 +0200 [thread overview]
Message-ID: <ac556638e1f4b4f9786c30ed0debc4a8@kernel.crashing.org> (raw)
In-Reply-To: <0C620F0B-92B0-4EBF-BC0C-49FD4D3D4323@freescale.com>
> Was looking at merging some code between ppc32 & ppc64 and noticed
> that in ppc32 we consider r13 to be part of the non-volatile register
> set. Is this really correct?
I believe so, yes.
> r13 is suppose to be sdata pointer in ppc32
sdata pointer is non-volatile by definition...
> and system thread id in ppc64.
The 64-bit kernel uses GPR13 as the PACA pointer, so it handles
it specially -- it treats the userland values of the register
as non-volatile, though.
> So I'm wondering should we really be considering it NV on ppc32?
Yeah. I'm sure there is some way to make the macro's identical
between 32- and 64-bit, though.
Segher
next prev parent reply other threads:[~2005-09-08 17:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-08 16:28 r13 is non-volatile? Kumar Gala
2005-09-08 17:01 ` Segher Boessenkool [this message]
2005-09-08 19:30 ` linas
2005-09-08 21:53 ` Benjamin Herrenschmidt
2005-09-09 1:30 ` Kumar Gala
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