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authorLinus Torvalds <torvalds@linux-foundation.org>2011-12-04 19:57:09 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2011-12-04 19:57:09 (GMT)
commit8e8da023f5af71662867729db5547dc54786093c (patch)
tree0108c8b0bac10268a3156aaf042466b8815d1330 /mm
parente5fd47bfab2df0c2184cc0bf4245d8e1bb7724fb (diff)
downloadlinux-8e8da023f5af71662867729db5547dc54786093c.tar.xz
x86: Fix boot failures on older AMD CPU's
People with old AMD chips are getting hung boots, because commit bcb80e53877c ("x86, microcode, AMD: Add microcode revision to /proc/cpuinfo") moved the microcode detection too early into "early_init_amd()". At that point we are *so* early in the booth that the exception tables haven't even been set up yet, so the whole rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy); doesn't actually work: if the rdmsr does a GP fault (due to non-existant MSR register on older CPU's), we can't fix it up yet, and the boot fails. Fix it by simply moving the code to a slightly later point in the boot (init_amd() instead of early_init_amd()), since the kernel itself doesn't even really care about the microcode patchlevel at this point (or really ever: it's made available to user space in /proc/cpuinfo, and updated if you do a microcode load). Reported-tested-and-bisected-by: Larry Finger <Larry.Finger@lwfinger.net> Tested-by: Bob Tracy <rct@gherkin.frus.com> Acked-by: Borislav Petkov <borislav.petkov@amd.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
0 files changed, 0 insertions, 0 deletions