[CentOS] /lib/firmware/microcode.dat update on CentOS 6

On 17/01/18 21:24, Valeri Galtsev wrote:
> Dear All,
> 
> An update just brought on my CenOS 6 boxes updated microcode.dat files:
> 
>   /lib/firmware/microcode.dat
> 
> Does anybody know off hand what (how critical) is that, as, if it is 
> related to most famous these days trouble with CPU hardware, I will need 
> to reboot relevant boxes to have new microcode loaded. But if it is not 
> that critical, it can wait till next reboot.
> 
> Thanks a lot and apologies for laziness (not looking into details of 
> this particular update myself).
> 

See:

https://access.redhat.com/errata/RHSA-2018:0093

Red Hat have rolled back the recent microcode updates for Spectre as 
they were causing instabilities in some systems.

Updated microcode was only made available for a relatively small number 
of CPUs so it might be the case that the your microcode was never 
actually updated, hence there is nothing to roll back in the latest 
release, so no need to panic about rebooting. Checking /var/log/messages 
should give you more clues when your microcode was actually last updated 
and allow you to determine if it was before or after the recent Spectre 
fiasco.