From: Damian Yerrick Newsgroups: comp.os.msdos.djgpp Subject: Re: tracking an elusive crash Organization: Pin Eight Software http://pineight.8m.com/ Message-ID: References: <39B28CA5 DOT 14799CC8 AT user DOT rose DOT com> X-Newsreader: Forte Agent 1.7/32.534 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 44 X-Trace: +rnM+lepIZVCamqgqhOeP73nE98QkitGACGy3wkN5DS+G5JonO8Dd6186Ud4GlwCqlfbEmXAf07I!MrPf4hJOnUI6hlk+Vb33KyR2qgV7Tt1JRUFBnD80Xs3nkGixIvUdLu54nadyNFXSenyWUeuGW1Ra!iSITvIE= X-Complaints-To: abuse AT gte DOT net X-Abuse-Info: Please be sure to forward a copy of ALL headers X-Abuse-Info: Otherwise we will be unable to process your complaint properly NNTP-Posting-Date: Sun, 03 Sep 2000 18:41:17 GMT Distribution: world Date: Sun, 03 Sep 2000 18:41:17 GMT Path: news.mv.net!newspeer.phoen-x.net!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.direct.ca!look.ca!paloalto-snh1.gtei.net!news.gtei.net!dfiatx1-snr1.gtei.net.POSTED!not-for-mail Xref: news.mv.net comp.os.msdos.djgpp:103140 On Sun, 03 Sep 2000 12:38:46 -0500, April wrote: >I am working with btree code based on a text book. I get an elusive >crash that I cannot track down nor get any useful info post-crash. > >djgpp gcc version 2.95.2 19991024 >win95 > >The worst crash reboots the computer, the second worst gives a fatal >error 'you program has commited an illegal instruction'. Obviously in >both cases there is no call stack to symify. You've hit upon a bug so bad it crashes Windows's DOS box. Try running it in plain DOS (press F8 right before the clouds come up when starting your computer) with CWSDPMI.EXE in your .../djgpp/bin folder. CWSDPMI is a bit better at catching null pointer and other memory bugs >I have tried to run the program in dos mode (ie. booted to dos) Good. >but the GPF gives no callstack, and if I can believe the IP address, >when I locate it in the map file I finaly created, it is inside >libc.a(exceptn.o). I recently had this happen to me: mine turned out to be a stack overflow from infinite recursion due to an invalid tree structure in a data file. >What can I try? Try increasing the stack size. If that helps (larger data sizes without a crash), try switching to an algorithm that uses less stack. Try printf() debugging so you can trace the flow of the program. -- MS (n) 1. A debilitating and surprisingly widespread affliction that renders the sufferer barely able to perform the simplest task. 2. A disease, multiple sclerosis (see). This is McAfee VirusScan. Add these two lines to your signature to prevent the spread of signature viruses. http://www.mcafee.com/