Date: Sat, 01 Jul 1995 18:03:48 +0000 From: Matt Thomas <matt@lkg.dec.com> To: hackers@freebsd.org Subject: Best way to diagnose system lockups? Message-ID: <199507011803.SAA09932@whydos.lkg.dec.com>
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I'm trying to debug why FreeBSD lockups when using a 4 port Ethernet controller. (it's a PCI board with 4 DC21040's sitting behind a DC21050 PCI-PCI bridge; it's UTP only). Note that UnixWare 2.0 works fine (I transferred many gigabytes over one of the bridged ports without a problem) with the board which leads me to believe this may be a problem with FreeBSD and not with the hardware. DDB is built into the kernel. I've modified kern_clock.c to add a watchdog into hardclock/softclock (if softclock is not called at least every 60 seconds, hardclock will force a panic; this is a standard technique that I've used over the years quite effectively). When the system locks up, neither DDB (via CTRL/ALT/ESC) nor hardclock (no watchdog panic fires) is called. The only way back is reset which of course doesn't result in any useful information. (damn it! I like machines with halt buttons (like a VAX or an Alpha). Sigh) (stepping through the system with DDB is not really effective which I don't know where the system is hanging; I've tried the obvious places in my driver). Getting an ICE or a bus monitor is impossible. The best guess is that my driver is triggering a bug somewhere else in FreeBSD. Any ideas on how to approach this? Matt Thomas Internet: matt@lkg.dec.com U*X Networking WWW URL: http://ftp.dec.com/%7Ethomas/ Digital Equipment Corporation Disclaimer: This message reflects my Littleton, MA own warped views, etc.
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