On Thu, Sep 04, 2003 at 09:16:23AM -0400, Don Bowman wrote: > > From: Mike Silbersack [mailto:[EMAIL PROTECTED] > > On Thu, 28 Aug 2003, Don Bowman wrote: > > > > > I have machdep.ddb_on_nmi=1. > > > I can drop into the debugger with the magic > > > key sequence. However, when i hit the NMI > > > jumper, i don't always go there. Sometimes > > > I do. > > > The system is 4-way SMP [2xHTT xeon processors] > > > with 4.7. > > > > > > Any suggestion on where my NMI might be going? > > > > Is your NMI about 106K in size, and does it have the subjects > > "Thank you", > > "Wicked screensaver" and others? If so, I think I know where it's > > going... > > ? > it was actually a serious question. The nmi header on > my board goes into the ICH-3 of my chipset, but shorting the > jumper out doesn't always enter the debugger. It does > sometimes. If I set the NMI_NOW bit in the ICH-3 I always > enter the debugger. I was curious if anyone else had seen > this behaviour.
I haven't kept quite up to date on my x86 hardware lately (read: in the past five to ten years), but I distinctly remember a time when everyone referred to x86's NMI as a joke: a non-maskable interrupt that anyone could mask using a simple CLI instruction. Not sure if this is still the case, others would have to say if today's processors still may get so wedged that a NMI request would simply be ignored. The other possibility is some kind of kernel mess-up, bad enough that an NMI does indeed reach the processor, the processor does invoke the NMI handler, yet the handler (DDB) is quite unable to actually do any useful work - messed up data structures and such. G'luck, Peter -- Peter Pentchev [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] PGP key: http://people.FreeBSD.org/~roam/roam.key.asc Key fingerprint FDBA FD79 C26F 3C51 C95E DF9E ED18 B68D 1619 4553 This sentence no verb.
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