From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17346 invoked by alias); 5 May 2003 14:27:16 -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 17339 invoked from network); 5 May 2003 14:27:15 -0000 Received: from unknown (HELO crack.them.org) (146.82.138.56) by sources.redhat.com with SMTP; 5 May 2003 14:27:15 -0000 Received: from nevyn.them.org ([66.93.61.169] ident=mail) by crack.them.org with asmtp (Exim 3.12 #1 (Debian)) id 19CgwI-0003i0-00; Mon, 05 May 2003 09:27:34 -0500 Received: from drow by nevyn.them.org with local (Exim 3.36 #1 (Debian)) id 19Cgvp-0007WK-00; Mon, 05 May 2003 10:27:05 -0400 Date: Mon, 05 May 2003 14:27:00 -0000 From: Daniel Jacobowitz To: Andrew Cagney Cc: Mark Kettenis , gdb-patches@sources.redhat.com Subject: Re: [PATCH/i386newframe/RFC] DWARF CFI frame unwinder Message-ID: <20030505142705.GA28866@nevyn.them.org> Mail-Followup-To: Andrew Cagney , Mark Kettenis , gdb-patches@sources.redhat.com References: <200305042207.h44M7gNG023734@elgar.kettenis.dyndns.org> <3EB5DBFF.6030009@redhat.com> <20030505034242.GA21263@nevyn.them.org> <3EB67056.4070209@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3EB67056.4070209@redhat.com> User-Agent: Mutt/1.5.1i X-SW-Source: 2003-05/txt/msg00063.txt.bz2 On Mon, May 05, 2003 at 10:08:22AM -0400, Andrew Cagney wrote: > > >> > >>This isn't right. It should return DW_AT_frame_base. However, since > >>dwarf2expr.c doesn't yet use these methods it doesn't [?] really matter. > >> Only affects ``info frame''. > > > >I don't think it should. > > Er ... > > >The frame's CFA is the basis for identifying the frame and locating > >saved registers in the CFI. It is always present when you have CFI. > > > >DW_AT_frame_base is the basis for locating saved variables and locals. > >It is generally present when you have DWARF-2 debug info. > > You and I went through all this not too long ago. frame-base is for > this high level thingie, frame-unwind is for the low level register > information. Then, as Mark said, it shouldn't be providing a frame base at all. The CFA information is not the right frame base, and the use of DW_AT_frame_base is exactly orthogonal to the use of CFI. > >The two are not necessarily related. I don't remember how we settled > >on providing DW_AT_frame_base. Possibly a debug info auxiliary to the > >function symbol or to the block. > > > > > >By the way, I don't remember something else I believe we've > >discussed... Does each target that wants to use the CFI unwinder have > >to add it in its gdbarch initialization? > > At present yes. > > Given the amount of upheval required before a target will work with this > code, it doesn't really matter. As I,and now Mark, discovered, it is > something of an all or nothing afair. Sure, makes sense to me. -- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer