Re: [PATCH v2] arch/x86: Fix boot_cpu_data.microcode version output

[Oleksandr Natalenko]

Hi.

On 01.08.2018 13:38, Prarit Bhargava wrote:
> > After this patch, do we preserve an original microcode version 
> > somewhere? If no,
> > why? Sometimes it is useful while debugging another crash because of 
> > faulty
> > microcode.
> Interesting, and thanks for bringing this up.  Oleksandr, under what
> circumstances would you want to know what the old version was.  AFAICS 
> it is no
> longer running and should not have an impact on the system?

Once the kernel log does not contain a printout regarding updated 
microcode anymore (because the log buffer is limited in size and can be 
overwritten) and once you have a vmcore, it is handy to use 
boot_cpu_data to compare the microcode version with the per-CPU value to 
find out that is was updated at all. Or, maybe, that can be inspected in 
another way now?

--
  Oleksandr Natalenko (post-factum)