Erik Mouw <mouw@xxxxxxxxxxxx> writes: >> With kernel 2.6.21, the last messages displayed on the console were those >> of SMP hotpluging -- something along the lines of hotplugging CPU #1 and >> enabling NOHZ operation. The messages show no errors; it just deadlocks. > > CPU hotplug with a laptop? I don't think you can hotplug an extra core > into a Core2 Duo CPU. Yes. Hotplugging is relevant to any SMP / CMP machine. (Mine is CMP obviously.) Certain bootup / shutdown / suspend to disk routines require UP kernel operation, and so the processor / core #1 is disabled as necessary. For example, the kernel boots only on core #0 and then enables itself on core #1. This is not physical hotplugging of a processor. This is the kernel enabling and disabling its own use of that core/processor. > CONFIG_HOTPLUG_CPU: > Say Y here to experiment with turning CPUs off and on, and to > enable suspend on SMP systems. CPUs can be controlled through > /sys/devices/system/cpu. > > Symbol: HOTPLUG_CPU [=y] It is very easy to perform manually while the system is live: # echo 0 > /sys/devices/system/cpu/cpu1/online # echo 1 > /sys/devices/system/cpu/cpu1/online > > Enable Soft Lockup detection, RT Mutex debugging, Lock Debugging, and > Spinlock debugging (all under Kernel hacking --> Kernel debugging). Be > sure to compile the kernel with frame pointers (also under kernel > hacking) so the backtraces will be reliable. > > Playing with the various sysrq combinations might also give interesting > information about what's wrong. 1/2 of those already enabled. Will investigate. Obviously ACPI debugging is enabled too. > > Try serial console or netconsole. Or take a picture of the screen with > a digital camera. > Thanks. -timotheus
Attachment:
pgpoH8LtVqk17.pgp
Description: PGP signature
