[issue1077] Kernel lockup with SMP on -HEAD

[Matthew Dillon]

:..
:results shocked me - only one motherboard was compatible with
:DragonFly, another 8 just hang kernel when I turn SMP on, /me tired
:with ACPICA_IO turned on and turned off - nothing changes. The only
:one motherboard, which works with DragonyFLY is rather old ASUS
:workstation model, based on i975 chipset, another 8 motherboards was
:from Intel,
:5 motherboards from S5000 series, S3210SHLX, D975XBX2 and one SR1500
:...
:with latest bios firmware.
:The hang I've noticed is extremely tricky to debug, I'm trying to find
:problem for 4 days already, but can't find solution. Hang usually
:occurs (as I could see visually) after detecting all devices, and
:before (or maybe slightly after) calling /sbin/init, at least before

    It kinda sounds like an interrupt routing issue.  Interrupts are a
    nightmare on the intel architecture and we pretty much depend on the
    BIOS to do the routing as our ACPI support doesn't do it.   Usually
    one can get a SMP kernel working either with the APIC_IO option or
    without the APIC_IO kernel compile option... one of the two combinations
    usually works.

    My guess is that the failure is occuring when the kernel enables
    interrupts, which usually occurs after the initial bus and device
    scan.  I can only guess, though.

    If you can boot it with a UP kernel it might be possible to compare
    the dmesg output from the UP boot with the dmesg output from a SMP
    boot.

						-Matt