The problem:

% dmesg | grep -i micro
Atom PSE erratum detected, BIOS microcode update recommended
Atom PSE erratum detected, BIOS microcode update recommended
microcode: CPU0 sig=0x106c2, pf=0x4, revision=0x208
microcode: CPU1 sig=0x106c2, pf=0x4, revision=0x208
microcode: Microcode Update Driver: v2.00 , Peter Oruba

I found out that some recent kernel that I loaded at an unknown time, was able to point out that I had ‘old’ microcode for my processor on my Aspire1 ZG5. I searched around for a BIOS upgrade, but since this is an older generation netbook, I quickly gave up when my searching yielded nothing useful. There is a userspace tool that you can use to ‘upgrade’ the microcode provided by Intel on every boot. In Gentoo Linux, that is called sys-apps/microcode-ctl. Simply install that and enable the init script on boot.

The output after:

% dmesg | grep -i micro
Atom PSE erratum detected, BIOS microcode update recommended
Atom PSE erratum detected, BIOS microcode update recommended
microcode: CPU0 sig=0x106c2, pf=0x4, revision=0x208
microcode: CPU1 sig=0x106c2, pf=0x4, revision=0x208
microcode: Microcode Update Driver: v2.00 , Peter Oruba
microcode: CPU0 updated to revision 0x218, date = 2009-04-10
microcode: CPU1 updated to revision 0x218, date = 2009-04-10

References:

• https://wiki.archlinux.org/index.php/Microcode
• [Flameeyes’s Weblog : Microupdates for microcodes][2]

Edit: Added a reference

[2]: http://blog.flameeyes.eu/2011/01/17/microupdates-for-microcodes