Microcode

What is a Microcode update

Processor microcode is akin to processor firmware. The kernel is able to update the processor's firmware without the need to update it via a BIOS update.

The blobs can be downloaded from Intel's website. 20130222 is their latest release.

"The microcode data file contains the latest microcode definitions for all Intel processors. Intel releases microcode updates to correct processor behavior as documented in the respective processor specification updates. While the regular approach to getting this microcode update is via a BIOS upgrade, Intel realizes that this can be an administrative hassle. The Linux Operating System and VMware ESX products have a mechanism to update the microcode after booting. For example, this file will be used by the operating system mechanism if the file is placed in the /etc/firmware directory of the Linux system."

Note: Arch Linux does not use /etc/firmware to process the update.

Updating microcode

Install either intel-ucode OR amd-ucode, depending on your processor vendor, and create a .conf file in /etc/modules-load.d/

Reboot your machine and then execute:

# dmesg | grep microcode

The output of this command should indicate the current version of your processor's microcode and whether any additional update was applied to it.

Note: Microcode updates via software are not persistent. In other words, one needs to apply them at each boot which is why it is placed in the MODULES array.

Note: With udev/systemd-tools 185-1 & kernel 3.4.2 microcode was loaded automatically on my AMD opteron system and i didn't have to add it manually to MODULES array.

Note: If you were a previous user of the microcode_ctl package, remove microcode from the DAEMONS array in /etc/rc.conf. microcode_ctl is no longer in Arch's repositories.

How to tell if a microcode update is needed

The best way to tell is to download and install the appropriate microcode update. First load the microcode module using modprobe.

# modprobe microcode

Then inspect dmesg, if it reports that an update was applied, the microcode in the BIOS of your motherboard predates the one in either intel-ucode or amd-ucode. Users should therefore use the microcode update!

Examples, note that in each case, the BIOS on the motherboard is the latest version from each respective vendor:

Intel X3360:

microcode: CPU0 sig=0x10677, pf=0x10, revision=0x705
microcode: CPU1 sig=0x10677, pf=0x10, revision=0x705
microcode: CPU2 sig=0x10677, pf=0x10, revision=0x705
microcode: CPU3 sig=0x10677, pf=0x10, revision=0x705
microcode: Microcode Update Driver: v2.00 <tigran@aivazian.fsnet.co.uk>, Peter Oruba
microcode: CPU0 updated to revision 0x70a, date = 2010-09-29
microcode: CPU1 updated to revision 0x70a, date = 2010-09-29
microcode: CPU2 updated to revision 0x70a, date = 2010-09-29
microcode: CPU3 updated to revision 0x70a, date = 2010-09-29

Intel E5200:

microcode: CPU0 sig=0x1067a, pf=0x1, revision=0xa07
microcode: CPU1 sig=0x1067a, pf=0x1, revision=0xa07
microcode: Microcode Update Driver: v2.00 <tigran@aivazian.fsnet.co.uk>, Peter Oruba
microcode: CPU0 updated to revision 0xa0b, date = 2010-09-28
microcode: CPU1 updated to revision 0xa0b, date = 2010-09-28

Intel Atom 330:

microcode: CPU0 sig=0x106c2, pf=0x8, revision=0x20d
microcode: CPU1 sig=0x106c2, pf=0x8, revision=0x20d
microcode: CPU2 sig=0x106c2, pf=0x8, revision=0x20d
microcode: CPU3 sig=0x106c2, pf=0x8, revision=0x20d
microcode: Microcode Update Driver: v2.00 <tigran@aivazian.fsnet.co.uk>, Peter Oruba
microcode: CPU0 updated to revision 0x219, date = 2009-04-10
microcode: CPU1 updated to revision 0x219, date = 2009-04-10
microcode: CPU2 updated to revision 0x219, date = 2009-04-10
microcode: CPU3 updated to revision 0x219, date = 2009-04-10

It is believed that the date returned corresponds to the date that Intel implemented a microcode update. This date does not correspond to the version of the the microcode database included in the package!

Which CPUs accept microcode updates

AMD CPUs

According to AMD's Operating System Research Center, these CPUs support microcode updates:

• AMD processor families 10h, 11h, 12h, 14h, and 15h

Intel CPUs

According to Intel's download center, the following CPUs support microcode updates:

• Intel® Atom™ Processor
• Intel® Atom™ processor for Entry Level Desktop PCs
• Intel® Celeron® Desktop Processor
• Intel® Core™ Duo Processor
• Intel® Core™ i3 Desktop Processor
• Intel® Core™ i3 Mobile Processor
• Intel® Core™ i5 Desktop Processor
• Intel® Core™ i5 Mobile Processor
• Intel® Core™ i7 Desktop Processor
• Intel® Core™ i7 Mobile Processor
• Intel® Core™ i7 Mobile Processor Extreme Edition
• Intel® Core™ i7 Processor Extreme Edition
• Intel® Core™ Solo processor
• Intel® Core™2 Duo Desktop Processor
• Intel® Core™2 Duo Mobile Processor
• Intel® Core™2 Extreme Mobile Processor
• Intel® Core™2 Extreme Processor
• Intel® Core™2 Quad Mobile Processor
• Intel® Core™2 Quad Processor
• Intel® Core™2 Solo Processor
• Intel® Pentium® 4 Processor Extreme Edition
• Intel® Pentium® 4 Processors
• Intel® Pentium® D Processor
• Intel® Pentium® M Processor
• Intel® Pentium® Processor Extreme Edition
• Intel® Pentium® Processor for Desktop
• Intel® Pentium® Processor for Mobile
• Intel® Setup and Configuration Software (Intel® SCS)
• Intel® vPro™ technology
• Intel® Xeon® Processor
• Intel® Xeon® Processor 3000 Sequence
• Intel® Xeon® Processor 5000 Sequence
• Intel® Xeon® Processor 6000 Sequence
• Intel® Xeon® Processor 7000 Sequence
• Intel® Xeon® processor E3-1200 Product Family
• Intel® Xeon® processor E5-1600 Product Family
• Intel® Xeon® processor E5-2400 Product Family
• Intel® Xeon® processor E5-2600 Product Family
• Intel® Xeon® processor E5-4600 Product Family
• Intel® Xeon® processor E7-2800 Product Family
• Intel® Xeon® processor E7-4800 Product Family
• Intel® Xeon® processor E7-8800 Product Family
• Intel® Z2460 Smartphone
• Mobile Intel® Celeron® Processors
• Mobile Intel® Pentium® 4 Processors - M