[9fans] Alpha bootloader "kernel stack not valid"

[cblack1@uiuc.edu]

I have an AlphaPC 164LX that I've decided to try Plan 9 on, but I've hit
a roadblock in my efforts. I've successfully compiled the binaries,
kernel, and bootloader on another machine, and found a network card that
works with the SRM bootp/tftp bootloader (Intel 82559, oddly enough).
Bootp works great, the loader loads, the loader loads its configuration
perfectly, but as soon as it gets the first block of the kernel, the
process gets a "kernel stack not valid halt". I've got the latest SRM
console, V5.8-1, and the Plan 9 sources are from the Plan 9 ISO image I
pulled down several days ago.

I've traced it down to the memmove() call on line 532 of
/sys/src/boot/alphapc/bootp.c (or at least I think that's where it is, I
mangled the file a bit in the process of debugging). Apparently any
access to 0x80400020 (The hard-coded load address in the Alpha kernel)
results in this error. I'm aware that the Intel 8255x isn't known to
work with Plan 9 on Alpha, but that shouldn't make a difference before
the kernel is actually loaded, should it? Any idea at which bits I
should begin poking?

~chip