[3.9-rc1 x86/microcode] Bug in CONFIG_MICROCODE_INTEL_EARLY=y

[Tetsuo Handa]

Tetsuo Handa wrote:
> Tetsuo Handa wrote:
> > Hello.
> > 
> > I can boot linux-next-20130205 using kernel config at
> > http://I-love.SAKURA.ne.jp/tmp/config-3.8-rc6-next-20130205 .
> > But I get VMware's virtual machine kernel stack fault (hardware reset) as soon
> > as kernel is loaded if CONFIG_DEBUG_VIRTUAL=y is added to the config above.
> > 
> > Since I don't get kernel stack fault if CONFIG_DEBUG_VIRTUAL=y is added to
> > kernel config generated by "make allnoconfig", I guess something is wrong with
> > code which is executed at very early stage of bootup.
> > 
> > Any clue?
> > 
> > Regards.
> > 
> 
> This bug is not yet fixed as of 3.9-rc1.
> Should I run git bisect?
> 
> Regards.
> 
I couldn't find the exact commit due to build failure, but I can guess that
this problem is triggered by early microcode loading changes, for this problem
happens only when CONFIG_MICROCODE_INTEL_EARLY=y on x86_32 kernel.

Candidate commits are:

  086fc8f8 "x86/tlbflush.h: Define __native_flush_tlb_global_irq_disabled()"
  e666dfa2 "x86/microcode_intel_lib.c: Early update ucode on Intel's CPU"
  a8ebf6d1 "x86/microcode_core_early.c: Define interfaces for early loading ucode"
  ec400dde "x86/microcode_intel_early.c: Early update ucode on Intel's CPU"
  63b553c6 "x86/head_32.S: Early update ucode in 32-bit"
  e6ebf5de "x86/common.c: load ucode in 64 bit or show loading ucode info in 32 bit on AP"
  d288e1cf "x86/common.c: Make have_cpuid_p() a global function"
  feddc9de "x86/head64.c: Early update ucode in 64-bit"
  9cd4d78e "x86/microcode_intel.h: Define functions and macros for early loading ucode"
  cd745be8 "x86/mm/init.c: Copy ucode from initrd image to kernel memory"
  da76f64e "x86/Kconfig: Make early microcode loading a configuration feature"

I'm using Intel(R) Core(TM) i5-2400 CPU @ 3.10GHz on VMware Player 4.0.5.

Regards.
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