From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.33)
	id 1CGilN-0002Bz-Vu
	for qemu-devel@nongnu.org; Sun, 10 Oct 2004 14:49:46 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.33)
	id 1CGilN-0002Bk-Gl
	for qemu-devel@nongnu.org; Sun, 10 Oct 2004 14:49:45 -0400
Received: from [199.232.76.173] (helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.33) id 1CGilN-0002BZ-B4
	for qemu-devel@nongnu.org; Sun, 10 Oct 2004 14:49:45 -0400
Received: from [213.80.72.10] (helo=kubrik.opensource.se)
	by monty-python.gnu.org with esmtp (Exim 4.34) id 1CGieR-00009S-HT
	for qemu-devel@nongnu.org; Sun, 10 Oct 2004 14:42:35 -0400
Received: from kubu (unknown [213.80.72.14])
	by kubrik.opensource.se (Postfix) with ESMTP id A985C3752C
	for <qemu-devel@nongnu.org>; Sun, 10 Oct 2004 20:30:33 +0200 (CEST)
Subject: Re: [Qemu-devel] /* XXX: suppress this hack */
From: Magnus Damm <damm@opensource.se>
In-Reply-To: <Pine.LNX.4.58.0410102021450.7539@wgmdd8.biozentrum.uni-wuerzburg.de>
References: <1097431180.15742.96.camel@kubu.opensource.se>
	<Pine.LNX.4.58.0410102021450.7539@wgmdd8.biozentrum.uni-wuerzburg.de>
Content-Type: text/plain
Message-Id: <1097434199.15737.111.camel@kubu.opensource.se>
Mime-Version: 1.0
Date: Sun, 10 Oct 2004 20:50:00 +0200
Content-Transfer-Encoding: 7bit
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org

Hello there, thanks for the reply!

[snip]

> > I would like to "suppress that hack", ie make sure that AREG4 to AREG11
> > gets defined for i386-softmmu. Someone that knows the code - what needs
> > to be done? Just removing the ifdef does not work for sure. Is it some
> > issue with setjmp()/longjmp()? I'm willing to set aside some hours to
> > fix this if someone who knows points me in the right direction.
> 
> It's all about ABIs: see
> 
> http://www-106.ibm.com/developerworks/linux/library/l-ppc/#h4
> 
> You want all those registers you use to be volatile, i.e. every function
> which wants to use one of those has to make sure that their original
> contents gets restored before returning.

Yeah, registers "r3" to "r12" are "caller save", ie these registers must
be saved before a function is called. But what about "r16" to "r23",
these are currently only used when CONFIG_USER_ONLY is set - I thought
that they were supposed to be saved by the called function prior use,
"callee save". But how does that affect the softmmu code in a bad way
but the user code works? Any ideas?

Thanks!

/ magnus