==> Regarding Re: [Wlug] HOWTO debug hard lockups; "Chuck R. Anderson" <cra@WPI.EDU> adds: cra> On Sun, Jun 05, 2005 at 10:35:13PM -0400, Andy Stewart wrote:
I've tried setting "nmi_watchdog=1" to see if I could get an "oops" when it hard locks - no dice. Do you know any other tricks I could try to see if it is the kernel which is locking up? I'm running SuSE's version of 2.6.8.
cra> Have you enabled the kernel Magic SysRq key and tried typing that when cra> it locks up? cra> sysctl -w kernel.sysrq = 1 cra> When it locks up: cra> Alt-SysRq-? for help, then try dumping the PC, Tasks, etc. You may cra> even be able to do an Emergency RO Mount and Sync before doing a Boot. This requires that you are not in X windows at the time of the lockup. See my other email in this thead. Also note that, due to no specific instances or facts to back up my statement, I don't like doing the 'Sync'. If the system is locked up, who is to say that you are going to write out valid data to the disk? I'd rather just reboot and let the journal recover things. -Jeff