Intel_Microcode

Modern processors ships with some kind of microcode inside the chips. There is a way for Intel's IA32 processors (all x86 and x86_64 processors) to update this microcode to workaround processor bugs.

Kernel support

Processor type and features  --->
    <M> /dev/cpu/microcode - Intel IA32 CPU microcode support

Userland support

Now install microcode-ctl:

emerge -av microcode-ctl

and update your microcode:

/etc/init.d/microcode_ctl start

Because the updated microcode can't be saved in the processor, you have to update the microcode on each boot. So just add microcode_ctl to your rc:

rc-update add microcode_ctl default