From mboxrd@z Thu Jan 1 00:00:00 1970 From: n0ano@n0ano.com Date: Tue, 29 Jun 2004 14:11:07 +0000 Subject: Re: Why large stack frame for PAL call Message-Id: <20040629141106.GA23246@tlaloc.n0ano.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 I can neither confirm nor deny these allegations (I think I've been watching CSPAN too much :-) I don't remember this code at all but my guess is that we did it to be overly conservative about saving registers. Back then, especially in a simulated environment, we didn't trust anything. As you say, most likely we didn't trust PAL to save things properly so we made sure it wouldn't be a problem. If PAL doesn't touch the stack registers then it should be safe to remove this. On Mon, Jun 28, 2004 at 10:50:15PM -0700, David Mosberger wrote: > >>>>> 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 > - > To unsubscribe from this list: send the line "unsubscribe linux-ia64" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Don Dugger "Censeo Toto nos in Kansa esse decisse." - D. Gale n0ano@n0ano.com Ph: 303/447-2201