In message <E1DHS2b-0000Xg-00@smeg.dsg.stanford.edu>, Jonathan Stone writes:
>The "IPI rendezvous failed" was *after* such a panic; you snipped the
>stacktrace and I already deleted my copy.  But I didn't see anything
>in the stacktrace leading to the original panic that yelled
>"smp-specific".

And I've verified that EXTMEM of 900*1024 makes it go away.  So I probably
need to set up serial console redirection (the motherboard has this, or I
can do it to the boot loader) and then set up a GENERIC kernel to get the
weird "... allocated..." message that's the VERY FIRST thing the kernel
says, even before it prints kernel version info.

Note that a GENERIC kernel on here, or any other not restricting EXTMEM,
won't run dmesg.  Some chunk of memory has been stolen by the motherboard.

-s