Ben Woodard <woodard at redhat.com> writes: > Eric W. Biederman wrote: >> Vivek Goyal <vgoyal at redhat.com> writes: >> >>> Ok. Got it. So in this case we route the interrupts directly through LAPIC >>> and put LVT0 in ExtInt mode and IOAPIC is bypassed. >>> >>> I am looking at Intel Multiprocessor specification v1.4 and as per figure >>> 3-3 on page 3-9, 8259 is connected to LINTIN0 line, which in turn is >>> connected to LINTIN0 pin on all processors. If that is the case, even in >>> this mode, all the CPU should see the timer interrupts (which is coming >>> from 8259)? >> >> However things are implemented completely differently now. I don't think >> the coherent hypertransport domain of AMD processors actually routes >> ExtINT interrupts to all cpus but instead one (the default route?) is >> picked. >> >> So I think for the kdump case we pretty much need to use an IOAPIC >> in virtual wire mode for recent AMD systems. >> >> For current Intel systems I believe either scenario still works. >> >>> Can you print the LAPIC registers (print_local_APIC) during normal boot >>> and during kdump boot and paste here? >> >> It's worth a look. >> >> I still think we need to just use apic mode at kernel startup, and >> be done with it. >> > > Neil whipped up a patch to try this and evidently it worked on his test boxes > but it didn't work very well on our problem tests box. It hung after the kernel > printed "Ready". i.e. on a normal boot I get: Interesting can you please try an early_printk console. I expect you made it a fair ways and it just didn't show up because you didn't get as far as the normal serial port setup. You don't have any output from your linux kernel. Eric
