Please test early update of microcode for AMD CPUs using an amd-microcode package.
 

Please find a package and instructions for testing in this repository. Top of the README below:
Rationale:

• Many (most) users do not keep their firmware up to date installing a new version when available, although these updates would alleviate security risks and functional issues.
• But the Linux Microcode Loader allows to instead update the microcode, either integrating the updated files in it or applying them at each boot, through an initrd file.
• It is preferable to use an initrd loaded early, to avoid having to rebuild a kernel every time new microcode files are available for either Intel or AMD.
• The updated microcode files (presented in a CIPO archive as an intrd file) can then either integrated in a main initrd (like the one that can write mknitrd or dracut) or be in /boot, loaded early by the boot loader.

For Slint GRUB will load the microcode early and this is my recommendation for Slackware 15.1 as well. This way grub.cfg will need to be updated only once (after the microcode file has been included in /boot for the first time) as its name won't change after an update.

I request testing of this package and method here because I can't test myself by lack of a computer with an AMD CPU and as this feature could be included in Slackware without any modification.

I do not request testing this method for Intel CPUs (using an intel-microcode package for which a SlackBuild is available) as I have successfully tested it myself

@Didier , Hmm , AM I mistaken that there is no documented procedure to include the package in a initrd ?
As I do not use Grub '.' , I use elilo , So an initrd is all that is available to atm .
Tia , JimL

You could adapt to elilo the method presented in https://wiki.archlinux.org/title/microcode for lilo.

Or use mkinitrd with the option -P, like that (according to the man page)
mkinitrd -P /boot/amd-ucode.img

Thanks, Didier. I'm getting a Zen4 (7940HS) based computer this week; will certainly use and test it out.

What is considered "early loading" on AMD?

Are the "Speculative Return Stack Overflow:" lines indication of early loading? The "microcode:" lines show up much later in the boot process.

I didn't use your package but I do use grub and an initrd without microcode. Just wondering...

Early microcode loading should happen at (or very near) the beginning of the boot. In fact, on this here Intel (with microcode prepended to the initrd using mkinitrd's "-P" option,) the microcode loading for CPU0 is the very first line in the dmesg output:

Though I can't say for sure, I would suspect similar results for AMD. Perhaps Didier can confirm or disconfirm this suspicion... :)

I confirm. According to https://www.kernel.org/doc/html/next/x86/microcode.html on AMD systems using early loading the output would look something like this:
So it seems that you need to either get a firmware update from your machine's vendor or apply the early microcode update at each boot, as proposed in this thread.

Caveat: not all AMD CPUs can have their microcode updated this way, this depends of AMD releasing a blob to be included in /lib/firmware for your model.

My search for microcode updates for my AMD Ryzen 5 5600G with Radeon Graphics (Zen 3) came up empty.

Looks like I can't help Didier test the proposed package.

Thanks for the attempt to include this in Slackware. Although kernel-firmware already brings it requiring some user steps to go, a dedicated package is much appreciated.

Test looks fine here:

/off-topic
Unfortunately a zenbleed fix in amd-ucode for anything other than servers is expected not before Nov'23 or Dec'23 (depending on the CPU model). Luckily linux kernel mitigates it at a performance penalty.

In case someone asks what is that 'smc' command, look here.

New build.
 

I have rebuilt the package just to include a few documents in it as indicated in the ChangeLog thanks to Debian and simplified its building thanks to Gentoo. Instructions for testing are now in README.testing.

It is indeed possible for a user to trigger an early update of the AMD microcode at each boot several ways, like building /boot/amd-ucode.img with a small script, or just running dracut, that includes kernel/x86/microcode/AuthenticAMD.bin by default in the initrd it creates from the files provided by the kernel-firmware package. The idea is "less maintenance work" for the user .

No need for anything but standard Slackware packages, namely kernel-firmware and libarchive. Just issue:

Nicely done, no external utils required. More at Gentoo's wiki.

Typo:

Corrected:

@denydias: thanks for the correction.

@All: please hold on, I think I made a mistake building the new package, will do a rebuild again.

New build again.
 

It just fixes the previous one.