Date: Wed, 8 Dec 2004 11:54:45 +0000 (GMT) From: Robert Watson <rwatson@freebsd.org> To: Michael Nottebrock <michaelnottebrock@gmx.net> Cc: freebsd-stable@freebsd.org Subject: Re: crashdumps not working Message-ID: <Pine.NEB.3.96L.1041208115235.98791H-100000@fledge.watson.org> In-Reply-To: <200412081241.19968.michaelnottebrock@gmx.net>
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On Wed, 8 Dec 2004, Michael Nottebrock wrote: > On Wednesday, 8. December 2004 12:20, Robert Watson wrote: > > On Tue, 7 Dec 2004, Michael Nottebrock wrote: > > > I recently enabled SW_WATCHDOG in my kernel, but when watchdog triggers > > > a panic, no crashdump is taken although dumps are enabled. What could be > > > causing this? > > > > If you drop to the debugger by using the debug.kdb.enter sysctl, and do > > "call doadump", followed by a reset, does a dump get generated > > successfully? > > I don't have kdb enabled in my kernel configuration at all... I'm guessing it might be useful at this point, if possible :-). Do you have a serial console on the box, or could you set one up? > > I.e., are they completely broken on your system, or is this > > somehow a property of the particular hang you're seeing. > > See my other mail, a different (non-watchdog) panic didn't trigger a dump > either. I even had the panic message in dmesg: > > kernel trap 12 with interrupts disabled > > Fatal trap 12: page fault while in kernel mode > fault virtual address = 0x14c > fault code = supervisor write, page not present > instruction pointer = 0x8:0xc0521397 > stack pointer = 0x10:0xe9794b84 > frame pointer = 0x10:0xe9794b90 > code segment = base 0x0, limit 0xfffff, type 0x1b > = DPL 0, pres 1, def32 1, gran 1 > processor eflags = resume, IOPL = 0 > current process = 1281 (beep-media-player) > trap number = 12 > panic: page fault This is a NULL pointer dereference; you can use addr2line or gdb on your kernel.debug to turn it into a line number even without a core. That might well be worth doing, as we might be able to debug that even without getting dumping working on the box. > Syncing disks, vnodes remaining...4 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 0 0 0 0 0 0 0 (I enabled kern.sync_on_panic only very recently for my > experimenting with watchdog, dumping didn't work without it either). Syncing on panic is, in general, probably not going to make it work better than not. I guess there's no chance the box has an NMI button? Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Principal Research Scientist, McAfee Research
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