Re: 2.6.22-rc1-mm1: strange GPF when panicing under kvm

Avi Kivity
2007-05-17T13:23:42Z

> When I boot 2.6.22-rc1-mm1 under kvm, but forget to specify a root
> filesystem, it panics as expected. However, when panicing, it gets a
> GPF in delay_tsc, and then starts recursively panicing.
>
> I don't really understand what's going on; the instruction it's faulting
> on seems to be "pause" (ie, rep;nop), which seems like it shouldn't
> fault at all. It looks like some kvm artifact to me, but I'm not sure.
>
> Hm, given the error code, maybe it's a segment register problem.
>
>

Strange. What does your msr 0x482 look like? If you have
/dev/cpu/0/msr, the following will spit it out:

-------------
#!/usr/bin/python

import struct

msrs = file('/dev/cpu/0/msr')
msrs.seek(0x482)
msr = msrs.read(8)
msr = struct.unpack('Q', msr)[0]

print '%x' % (msr,)
----------------

(that msr can force trapping of the pause instruction, even though
there's no good reason to do it, and kvm wouldn't inject a gp if it did
anyway).

--
error compiling committee.c: too many arguments to function