Re: [gentoo-user] AMD microcode updates - where are they?!

[Mick]

On Saturday, 13 July 2019 17:21:40 BST Jack wrote:
> On 2019.07.12 08:18, Mick wrote:

> > https://www.bleepingcomputer.com/news/hardware/amd-releases-spectre-v2-mic
> > rocode-updates-for-cpus-going-back-to-2011/
> I have not yet done any further searching or digging, but that link
> seems to only talk specifically about Windows updates, not generic
> firmware updates.

Yes, but any microcode releases are/should be CPU specific.  If they're 
released for applying via one OS, they should be available to others too.

Of course, if microcode has only been released to MoBo OEM's, then we're in 
the mercy of OEM commercial interests.  I'm sure when asked for an update they 
will try to sell to us all the latest models they have recently launched.  :p


> I have three different AMD based PCs, and so far, I don't see anything
> different from Mick.  However, on two Artix linux systems, I'm still
> not quite sure whether the microcode is in the initramfs or not.  I
> hate to admit I'm also not sure on my Gentoo box, having so far made
> only minor changes to the kernel from the June stage 3 tarball, and
> used genkernel to compile both kernel and initramfs.  I'm working on
> configuring 5.2.0, but it will take me a while to get through the
> complete configuration (starting from scratch.)

I'm not familiar with dracut to know what it uses as a default archiving 
engine and if you can run it to inspect directly the contents of an already 
created initramfs.  I know it can output on the console what it is including 
in initramfs at the time of creation.

Anyway, if you want to look at the initramfs contents manually, I suppose you 
will need to decompress your initramfs in a temporary directory to see its 
contents.  First find what archive format has been used.  

file /boot/EFI/... initramfs-XXX.img

will output gzip, bzip2, lzma or similar archive type.  Then create a 
temporary directory to work in and use the corresponding compression type:

mkdir ~/tmp_initramfs
cd ~/tmp_initramfs

zcat /boot/EFI/... initramfs-XXX.img | cpio -idmv

or 

bzcat /boot/EFI/... initramfs-XXX.img | cpio -idmv

or 

xv -dc < /boot/EFI/... initramfs-XXX.img | cpio -idmv

Something like the above ought to do the job.

> One suggestion - don't just grep for microcode, also check for
> "firmware" for which I use 'dmesg | egrep -i "firmware|microcode"'.

Well, 'firmware' will capture other firmware files, like graphics card, WiFi, 
BT, etc. rather than the CPU microcode.


> And, one question - if I have linux-firmware emerged with savedconfig
> use flag set, what's the best/easiest way to hunt through the actually
> available firmware, to check if I might have missed something
> relevant.  So far, I've just searched the git repository for the
> package.  I suppose I could have kept a copy of the manifest from the
> initial emerge (without savedconfig)  but I didn't think of it at the
> time.
>
> Jack

Look under your /lib/firmware/ directory for the file you want to use, or the 
file dmesg complains is missing.  For microcode there will be no complaining, 
but for other hardware there usually is something along the lines:  "failed to 
load blah-blah.bin, file not found."

The appropriate microcode file for your AMD CPUs can be deduced from the table 
here:

https://wiki.gentoo.org/wiki/AMD_microcode

and it should be stored under your:

/lib/firmware/amd-ucode/

after you install linux-firmware.

-- 
Regards,

Mick