On Wed, Nov 07, 2007 at 09:00:06AM -0500, Neil Horman wrote: > Hey all- > I've been getting reports of some x86_64 systems that, on kdump kernel > boot get stuck in calibrate_delay(), in both RHEL kernels and upstream kernels. > The current thinking is that the lapic timer interrupt is no longer getting > delivered, likely because we handle a crash condition on a cpu that isn't the > boot cpu. One known offender is this motherboard: > http://www.supermicro.com/Aplus/motherboard/Opteron8000/MCP55/H8QM8-2.cfm > My current thought is that the TIMER_LVT entry is masked on all but the boot cpu > on this system (which is strange, as I was under the impression that the timer > interrupt was supposed to be enabled on all CPU's nominally. I also thought that LAPIC timer interrupts are enabled on all cpus. > At any rate, I was > going to try to read/write the TIMER_LVT on the crashing processor before we > jump to purgatory, or in purgatory itself, to see if that fixes the problem, but I think calibrate_dealy() depends on external timer interrupt coming and not the local APIC timer interrupt. Generally it is 8254 timer chip. Now a days motherboards seems to be having HPET and I know somebody has reported problems with HPET where HPET interrupts are not coming in second kernel and system hangs in second kernel. I suspect that same might be the issue here. Thanks Vivek
