I was partially right.
TL;DR:
- Method with
/lib/firmware/intel-ucode/* works.
- It required "echo 1 > ..." both for load and reload the microcode.
I used the latest SliTaz Next image I have without microcode files. Kernel in the SliTaz Next is already configured in the same way like Pascal was commited here (and Pascal's commit isn't wrong). Results from the commandline:
$ dmesg | grep microcode
[ 23.680263] microcode: sig=0x6fd, pf=0x80, revision=0xa1
[ 23.680423] microcode: Microcode Update Driver: v2.01 <tigran@aivazian.fsnet.co.uk>, Peter Oruba
Then I added the microcode files to /lib/firmware/intel-ucode/ and recreated the ISO. Results from the commandline:
$ dmesg | grep microcode
[ 23.814499] microcode: sig=0x6fd, pf=0x80, revision=0xa1
[ 23.814639] microcode: Microcode Update Driver: v2.01 <tigran@aivazian.fsnet.co.uk>, Peter Oruba
Looks pretty the same. No microcode was updated automatically during the booting.
I checked the system have the file /sys/devices/system/cpu/microcode/reload and then run the command from the root commanline:
# echo 1 > /sys/devices/system/cpu/microcode/reload
Try again:
$ dmesg | grep microcode
[ 23.814499] microcode: sig=0x6fd, pf=0x80, revision=0xa1
[ 23.814639] microcode: Microcode Update Driver: v2.01 <tigran@aivazian.fsnet.co.uk>, Peter Oruba
[ 142.448548] microcode: updated to revision 0xa4, date = 2010-10-02
Now the CPU has updated the microcode.
And there also the beginning of the cpuinfo:
$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 Duo CPU T5670 @ 1.80GHz
stepping : 13
microcode : 0xa4
So, Kernel used the file /lib/firmware/intel-ucode/06-0f-0d for my CPU (based on <cpu family>-<model>-<stepping> numbers in the hex format).
What's next?
I think I should add the command "echo 1 > ..." to the /etc/init.d/system.sh.
It should check existence of the control file /sys/devices/system/cpu/microcode/reload.
And I think it is better to provide Kernel commandine option like "nomc" or "nomicrocode" or even "no-microcode-update" to disable this command (echo 1 ...) execution because the system may become unstable with the latest versions of the Intel CPUs like they say here and there over the internet...
