From owner-cvs-all Wed May 1 12:38:13 2002 Delivered-To: cvs-all@freebsd.org Received: from kayak.xcllnt.net (209-128-86-226.bayarea.net [209.128.86.226]) by hub.freebsd.org (Postfix) with ESMTP id B8ED537B419; Wed, 1 May 2002 12:37:57 -0700 (PDT) Received: from athlon.pn.xcllnt.net (athlon.pn.xcllnt.net [192.168.4.3]) by kayak.xcllnt.net (8.11.6/8.11.4) with ESMTP id g41JbJJ06164; Wed, 1 May 2002 12:37:19 -0700 (PDT) (envelope-from marcel@kayak.pn.xcllnt.net) Received: from athlon.pn.xcllnt.net (localhost [127.0.0.1]) by athlon.pn.xcllnt.net (8.12.3/8.12.2) with ESMTP id g41JbJO8000754; Wed, 1 May 2002 12:37:19 -0700 (PDT) (envelope-from marcel@athlon.pn.xcllnt.net) Received: (from marcel@localhost) by athlon.pn.xcllnt.net (8.12.3/8.12.3/Submit) id g41JbJAw000753; Wed, 1 May 2002 12:37:19 -0700 (PDT) Date: Wed, 1 May 2002 12:37:19 -0700 From: Marcel Moolenaar To: Doug Rabson Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/ia64/ia64 exception.s src/sys/ia64/include frame.h Message-ID: <20020501193719.GA699@athlon.pn.xcllnt.net> References: <200204300637.g3U6bQc25956@freefall.freebsd.org> <200205010940.33776.dfr@nlsystems.com> <20020501181758.GB415@athlon.pn.xcllnt.net> <200205012015.32377.dfr@nlsystems.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200205012015.32377.dfr@nlsystems.com> User-Agent: Mutt/1.3.27i Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Wed, May 01, 2002 at 08:15:32PM +0100, Doug Rabson wrote: > > > > > > What I actually meant by that statement was that since the exception > > > entry path didn't disturb the value of ar.lc (or ar.ec for that matter) > > > and that it can rely on the value being preserved by the higher level > > > handlers (e.g. trap, interrupt, syscall etc), it can also rely on the > > > value in > > > exception_restore being the user's value. > > > > That is correct, provided we save them on context switches, right? > > Right. Ok, I'll add them to savectx() and cpu_switch() then :-) > > > > BTW: The reason I added them was for ptrace(2). > > Thats as good a reason as any. Another way would be to use the unwind system > to find if/where the register had been saved and access it either directly or > at the save location. Wicked! I'll let this run through my head for a while. My first reaction is that it sounds like a very costly approach, time and complexity wise. For example: if ar.lc has been saved in the process' pcb, then there's no way the unwind information can tell us that. We need to handle those cases seperately, AFAICT. -- Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message