DragonFly kernel List (threaded) for 2012-03
Re: AMD cpu bug update #3 -- Official AMD reference now available
As a followup, here is our simplified test case:
movq $80, %r8
compile main.c and ras.s (gcc main.c ras.s) and run ./a.out; you may
quickly see %rsp updated incorrectly, which will likely manifest as a
segmentation fault. The fault is fairly sensitive to stack alignment,
so you may need to run it a few times to hit it; simply cancel the run
and try again.
This errata affects all AMD K10 CPUs; Families 10h and 12h. It does
not affect family 15h (Bulldozer).
There is a workaround -- setting bit 0 of MSR 0xc0011029. DragonFly
just got a patch to do so, expect other systems to follow suit soon.