From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19174 invoked by alias); 23 Oct 2003 23:23:01 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 19164 invoked from network); 23 Oct 2003 23:23:00 -0000 Received: from unknown (HELO ns1.xcllnt.net) (209.128.86.226) by sources.redhat.com with SMTP; 23 Oct 2003 23:23:00 -0000 Received: from dhcp01.pn.xcllnt.net (dhcp01.pn.xcllnt.net [192.168.4.201]) by ns1.xcllnt.net (8.12.9/8.12.9) with ESMTP id h9NNMpbe059968; Thu, 23 Oct 2003 16:22:51 -0700 (PDT) (envelope-from marcel@piii.pn.xcllnt.net) Received: from dhcp01.pn.xcllnt.net (localhost [127.0.0.1]) by dhcp01.pn.xcllnt.net (8.12.10/8.12.10) with ESMTP id h9NNMpLd014706; Thu, 23 Oct 2003 16:22:51 -0700 (PDT) (envelope-from marcel@dhcp01.pn.xcllnt.net) Received: (from marcel@localhost) by dhcp01.pn.xcllnt.net (8.12.10/8.12.10/Submit) id h9NNMpQ4014705; Thu, 23 Oct 2003 16:22:51 -0700 (PDT) (envelope-from marcel) Date: Thu, 23 Oct 2003 23:23:00 -0000 From: Marcel Moolenaar To: Kevin Buettner Cc: "J. Johnston" , gdb-patches@sources.redhat.com Subject: Re: RFA: ia64 tdep patch Message-ID: <20031023232251.GA14660@dhcp01.pn.xcllnt.net> References: <3F9049EF.8060209@redhat.com> <1031020201315.ZM20659@localhost.localdomain> <3F9459B6.5000909@redhat.com> <1031021222239.ZM26261@localhost.localdomain> <3F95BB43.1040703@redhat.com> <1031022193747.ZM31624@localhost.localdomain> <3F96EF3E.6070402@redhat.com> <20031022220258.GA10464@dhcp01.pn.xcllnt.net> <1031023210049.ZM1243@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1031023210049.ZM1243@localhost.localdomain> User-Agent: Mutt/1.5.4i X-SW-Source: 2003-10/txt/msg00710.txt.bz2 On Thu, Oct 23, 2003 at 02:00:49PM -0700, Kevin Buettner wrote: > On Oct 22, 3:02pm, Marcel Moolenaar wrote: > > > > They are needed because r32 to r127 are not accessible via the PTRACE > > > interface. They are accessed via the bsp. Without flagging them as > > > pseudo-registers, the regcache code returns 0 for all these registers. > > > > It depends. For FreeBSD I added ptrace(2) functions to get and set > > stacked registers that are on the kernel stack. The problem more > > generally is that registers above bspstore (but below bsp) are > > not accessable in memory. I think it's better for gdb to keep the > > distinction between stacked registers on the backing store and > > "dirty" stacked registers. The distinction avoids that gdb makes > > assumptions that are only valid on Linux or even only for the native > > code. > > Unfortunately, the assumptions that you mention are already in place. > (And have been in place for quite some time). Yes, and it is one of the pickles I'm working on. Do I change FreeBSD to match the assumption in gdb or do I change gdb to remove the assumption? One technical reason for removing the assumption in gdb is that it is not always possible to flush the dirty registers onto the user backing store. It could fail when BSPSTORE is close to or at the boundary of the register stack. This is a border case, but it would be impossible to debug a process when it actually operates under these conditions. Also, when flushing the dirty registers onto the user backing store, we change the state of the process, which may hide the problem and interfere with debugging. It's mostly academic, but still a fundamental "flaw" in debugging on ia64. A technical reason for changing FreeBSD is that it avoids changing gdb and keeps access to the stacked registers uniform. However, even though debugging is not performance critical, moving the complexity into the debugger may avoid unnecessary and unconditional copying from the kernel stack to the user stack and gives gdb (or any other program that needs this) control over it... I'm leaning towards changing gdb. I just need to underdstand better what I'm getting into. I have little experience with gdb... > > BTW: I have partial support for FreeBSD/ia64. I'll send patches as > > soon as I feel that the backtrace is reliable enough. > > Patches will most certainly be welcome. Do you have an FSF copyright > assignment for GDB yet? If not, you might want to start working on > the paperwork now... I do not have such assignment, but it's in the pipeline. -- Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net