From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29674 invoked by alias); 30 Aug 2002 03:37:40 -0000 Mailing-List: contact gdb-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sources.redhat.com Received: (qmail 29664 invoked from network); 30 Aug 2002 03:37:39 -0000 Received: from unknown (HELO localhost.redhat.com) (66.30.197.194) by sources.redhat.com with SMTP; 30 Aug 2002 03:37:39 -0000 Received: by localhost.redhat.com (Postfix, from userid 469) id F2260108F6; Thu, 29 Aug 2002 23:35:43 -0400 (EDT) From: Elena Zannoni MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15726.59407.855138.718609@localhost.redhat.com> Date: Thu, 29 Aug 2002 20:37:00 -0000 To: Christopher Faylor Cc: gdb@sources.redhat.com Subject: Re: SEGV on display /i $pc with i386 target In-Reply-To: <20020830010539.GA28337@redhat.com> References: <20020829055103.GA26149@redhat.com> <86k7m9p9v9.fsf@elgar.kettenis.dyndns.org> <20020830010539.GA28337@redhat.com> X-SW-Source: 2002-08/txt/msg00409.txt.bz2 Christopher Faylor writes: > On Fri, Aug 30, 2002 at 12:40:10AM +0200, Mark Kettenis wrote: > >Christopher Faylor writes: > >>I just noticed a SEGV whenever I do a 'display /i $pc' on cygwin. > >> > >>I tried building a gdb for linux to see what was going wrong on cygwin > >>but it isn't much better: > >> > >>(top-gdb) display /i $pc > >>1: x/i $(null) 0x8072f42 : push $0x6 > >> > >>The problem comes from the fact that, while gdb understands that $pc == > >>$eip, it doesn't seem to know how to rename $pc to $eip when it is > >>outputting the register name. You can get the same behavior by doing > >>something like 'display /i $ps', too (even if that doesn't make sense > >>it shouldn't SEGV). > > > >Hmm, this defenitely used to work in the past. Does anybody have an > >idea what broke it? > > I tested cygwin releases that I generated all the way back to April and > saw that, while there were no SEGVs on cygwin, I was getting bogus > output where I saw something like $xmmi used rather than $eib in the > display. > > Maybe Andrew's 2002-08-13 change to i386_register_name may have stopped > that from occuring and, essentially, stopped masking some broken > behavior. > > >>The simplest way to fix this is to extend the i386_register_names array > >>to include builtin register names, however, maybe the right way to fix > >>this is to add something to builtin-reg.c. > > > >I suspect this problem isn't i386-specific, so extending > >i386_register_names seems to be the wrong approach to me. > > I agree. Seems like target_map_name_to_register is the problem? Something to do with register aliases was changed between 1.17 and 1.18 versions of parse.c and between 1.21 and 1.22. (a shot in the dark) Elena > > >> I noticed that i386_register_names seems to have 41 elements while > >> the sum of NUM_REGS + NUM_PSEUDO_REGS == 40. Is that intentional? > > > >Sort of. In the current situation, Depending on whether your target > >supports the SSE registers NUM_REGS will be either 32 or 41. Since > >NUM_PSEUDO_REGS is 6, and 32 + 6 = 40. > > > >Perhaps this is a good moment to warn you about an implication of > >multi-arching the i386 for Cygwin: the Cygwin targets don't support > >SSE anymor, since we use the "Unknown" OS/ABI for Cygwin right now. I > >doubt whether this is what you want. You probably want to introduce > >some sort of Cygwin or Win32 OS/ABI that includes those registers. > > I noticed that while I was poking at this. I'll put this on my > long todo list. > > cgf