From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Tue, 29 Jun 2004 05:50:15 +0000 Subject: Re: Why large stack frame for PAL call Message-Id: <16609.791.65478.362755@napali.hpl.hp.com> List-Id: References: <200406271740.i5RHeaY24803@unix-os.sc.intel.com> In-Reply-To: <200406271740.i5RHeaY24803@unix-os.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Sun, 27 Jun 2004 10:42:14 -0700, "Chen, Kenneth W" said: Ken> Does anyone know why we need such large stack frame for PAL Ken> static call? PAL isn't even suppose to touch any stack Ken> register for static calling convention. Is it for legacy Ken> reason or something? Good question. I was able to track the source down to a patch that was sent to me by Walt Drummond on Aug 11, 1999. The authors listed in the relevant file (it was called palcall.S back then) were Don Dugger and Walt Drummond (in this order), so my guess is the code was originally written by Don. At that time, the primary target for Don would have been SoftSDV. Perhaps it was to work around a bug in SoftSDV, though I suspect it's just as likely that the code came about by a misunderstood/misdocumented PAL-requirement. Perhaps Don or Asit remember how this came about? I also cannot find a requirement that would demand allocating 96 stacked registers before making a PAL call and I'd be in favor of cleaning that up. --david