Comment # 81 on bug 913996 from Borislav Petkov

So basically 13.2 has never applied microcode successfully on that box,
correct? Not even the installer kernel works.

Ok, here's what you can try:

* copy /lib/firmware/amd-ucode somewhere safe

* remove the ucode-amd package

* install the latest kernel-desktop or -default. dracut should not find
the microcode, pay attention to this message:

*** Generating early-microcode cpio image ***
*** Constructing AuthenticAMD.bin ****

it should *not* be printed.

* remove "dis_ucode_ldr" from the kernel parameters

* boot the new kernel

* The machine should be up, when it is, move the stashed
/lib/firmware/amd-ucode folder back in its place, i.e.
/lib/firmware/amd-ucode

* As root, do

echo 1 > /sys/devices/system/cpu/microcode/reload

* Send me dmesg

If this works out, this should show that microcode gets updated late on
that machine.

Thanks.