On Sat, May 27, 2006 at 05:13:21PM -0400, Kumba wrote: > Finally managed to track down the git commit causing SGI IP32 (O2) systems > to lock up really early in the boot cycle, but I'm at a loss to understand > why. > > Effect: > It appears the system silently hangs somewhere in the void between function > calls when trying to invoke the memset() call in __alloc_bootmem_core() in > mm/bootmem.c. This puts the machine hardware in a state such that a simple > soft reset doesn't clear it -- the machine has to be cold booted to get it > to boot a working kernel again. > > Determined Cause: > It seems this commit: > 78eef01b0fae087c5fadbd85dd4fe2918c3a015f > [PATCH] on_each_cpu(): disable local interrupts > > Is the cause. I've verified this by reversing this one change on a > 2.6.17-rc4 tree, and it'll boot to a mini-userland (initramfs-based) and > appears to function normally. > > > But this is as far as I can trace this. I'm not sure what this change is > doing internally that's triggering this lockup on O2 systems. It doesn't > appear to affect Octane (IP30) systems or Origin (IP27). I haven't > test-ran it on IP22/IP28 hardware yet, so only IP32 is known to be > affected. Unsure about non-SGI MIPS hardware. on_each_cpu is re-enabling interrupt. This may crash the system if it happens before interrupt handlers have been installed. A while ago I've fixes all such calls but I may have missed some instances. Andrew, what was the reason for 78eef01b0fae087c5fadbd85dd4fe2918c3a015f ? Ralf
