[Xen-devel] Xen c/s 18938

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

I am observing some odd boot behavior resulting from the changes done
in this c/s. In particular am I seeing banks being initialized inconsistently on
my dual quad-core system:
- after a cold boot, CPU0 has all its MCi_CTL non-zero (apparently BIOS-
  initialized), while CPUs 1, 4, and 5 have MC1_CTL non-zero but the others
  zero, and the remaining CPUs have MC1_CTL and MC3_CTL non-zero
  (MC3 presumably is non-zero here indeed because of it being shared
  across two of the four cores)
- after a warm boot, all of the CPUs have all their MCi_CTL registers except
  for MC3_CTL non-zero, so only bank 3 actually gets initialized (and
  reported - again not for CPUs 0, 2, 3, 6, and 7).

I'm pretty certain that there should neither be a difference between cold
and warm boot here, nor should CPU0's BIOS settings (and any other CPUs'
if the BIOS cares to touch them) survive (specifically also resulting in
MCi_STATUS not being cleared). The old code simply wrote all ones and all zeros
respectively to MCi_CTL and MCi_STATUS without checking their original values.

Jan


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