From mboxrd@z Thu Jan 1 00:00:00 1970 Path: main.gmane.org!not-for-mail From: "Eli Zaretskii" Newsgroups: gmane.emacs.devel Subject: Re: Mac OSX running Carbon crash with today's CVS Date: Wed, 23 Apr 2003 11:54:28 +0200 Sender: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Message-ID: <7999-Wed23Apr2003115428+0300-eliz@elta.co.il> References: <37111A44-74D0-11D7-A77C-00039375B5CC@apple.com> Reply-To: Eli Zaretskii NNTP-Posting-Host: main.gmane.org X-Trace: main.gmane.org 1051088370 29749 80.91.224.249 (23 Apr 2003 08:59:30 GMT) X-Complaints-To: usenet@main.gmane.org NNTP-Posting-Date: Wed, 23 Apr 2003 08:59:30 +0000 (UTC) Cc: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Wed Apr 23 10:59:29 2003 Return-path: Original-Received: from quimby.gnus.org ([80.91.224.244]) by main.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 198G6D-0007jh-00 for ; Wed, 23 Apr 2003 10:59:29 +0200 Original-Received: from monty-python.gnu.org ([199.232.76.173]) by quimby.gnus.org with esmtp (Exim 3.12 #1 (Debian)) id 198GBs-0000hS-00 for ; Wed, 23 Apr 2003 11:05:20 +0200 Original-Received: from localhost ([127.0.0.1] helo=monty-python.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.10.13) id 198G6T-0000rC-00 for emacs-devel@quimby.gnus.org; Wed, 23 Apr 2003 04:59:45 -0400 Original-Received: from list by monty-python.gnu.org with tmda-scanned (Exim 4.10.13) id 198G67-0000pX-00 for emacs-devel@gnu.org; Wed, 23 Apr 2003 04:59:23 -0400 Original-Received: from mail by monty-python.gnu.org with spam-scanned (Exim 4.10.13) id 198G65-0000of-00 for emacs-devel@gnu.org; Wed, 23 Apr 2003 04:59:22 -0400 Original-Received: from bilbo.inter.net.il ([192.114.186.18]) by monty-python.gnu.org with esmtp (Exim 4.10.13) id 198G4S-0008UR-00 for emacs-devel@gnu.org; Wed, 23 Apr 2003 04:57:40 -0400 Original-Received: from zaretsky (cable-131-74.inter.net.il [213.8.131.74]) by bilbo.inter.net.il (Mirapoint Messaging Server MOS 3.2.2-GA) with ESMTP id AMR08681; Wed, 23 Apr 2003 11:57:34 +0300 (IDT) Original-To: gabriel@apple.com X-Mailer: emacs 21.3.50 (via feedmail 8 I) and Blat ver 1.8.9 In-reply-to: <37111A44-74D0-11D7-A77C-00039375B5CC@apple.com> (message from Gabriel Foster on Tue, 22 Apr 2003 07:39:25 -0700) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1b5 Precedence: list List-Id: Emacs development discussions. List-Help: List-Post: List-Subscribe: , List-Archive: List-Unsubscribe: , Errors-To: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Xref: main.gmane.org gmane.emacs.devel:13385 X-Report-Spam: http://spam.gmane.org/gmane.emacs.devel:13385 > Date: Tue, 22 Apr 2003 07:39:25 -0700 > From: Gabriel Foster > > In the most recent case, I had just hit the enter key. Can you cause the same crash if you type "M-x garbage-collect RET" right after starting Emacs? > (gdb) print tail > $2 = (struct gcpro *) 0xbfffde20 > (gdb) print *tail->var[i] > Cannot access memory at address 0x1 > (gdb) print tail->var[i] > Cannot access memory at address 0x1 > (gdb) print tail->var > $3 = (volatile int *) 0x1 This is the problem, then: either tail->var or tail->nvars is garbled (I'm guessing it's the latter). Does anyone have a clue why this could happen on a Mac? If no one comes up with a better idea, one way of attacking this bug would be to put a hardware-assisted watchpoint on the nvars member, like this: (gdb) watch ((struct gcpro *)0xbfffde20)->nvars and when the watchpoint fires, look for the code that puts the preposterously large value into nvars. (If nvars changes its value to something reasonable, like zero or 1, just type "cont" to let the program resume its run.) Before you do the above, it is highly recommended to find a simple procedure that would predictably cause such a crash, and with the same value of `tail', the GCPRO structure that is garbled. Then use that address instead of 0xbfffde20 above. (I'm assuming that GDB on Mac OSX supports hardware-assisted watchpoints, btw.)