the APM-bios.
This stabilizes a couple of APM bioses quite a bit.
They all make the mistake of going into 16-bit mode, without clearing the
top half of the 32bit registers.
Later they do a
| movw %si,$0x7331
| movw %ax,0x6(%si)
or something along those lines and crash and burn, because their segment
is already relocated, so adding 0xf0171ce9 to the base of it is bad news.
At least SystemSoft is guilty of this bummer.
I think I have narrowed this down to the stack being overflown. I have
taken the push/pop of %fs out, it shouldn't be needed anyway, but the
real & correct solution might to save the registers on the stack in
locore.s before calling this stuff.
