Re: [Xen-users] ucode=-1: did anybody have success?

[Sven Köhler <sven.koehler@xxxxxxxxx>]

Am 06.05.2014 21:39, schrieb Atom2:
> Am 06.05.14 15:27, schrieb Sven Köhler:
>> Or maybe the file is taken from /lib/firmware/intel-ucode/ and is copied
>> to the initrd when it is updates?
> The truth is that you can't use the microcode.dat file directly - this
> is a text file whereas the CPU expects a binary file.

It's a pity the hypervisor doesn't understand the microcode.dat format.

> You should be able
> to do 'cat /lib/firmware/intel_ucode/* > /boot/microcode.blob'
> and that should do it - although I have used another approach that
> results in a much smaller blob file: My file is now onyl 10,240 bytes as
> opposed to 576,512 bytes compared to cat /lib/firmware/... as described
> above) as it only contains the required binary files for my specific CPU:

The "cat /lib/firmware/intel_ucode/* > /boot/microcode.blob"-approach
seems dangerous to me. Are you sure, that simply concatenating the files
leaves you with a valid database?

I think it's safer to use the iucode-tool. The following command simply
converts microcode.dat to the binary format, right?

  ./iucode_tool -w /boot/microcode.blob /lib/firmware/microcode.dat

Can you confirm that /lib/firmware/intel-ucode/06-25-02 (for example)
is the file that contains all microcode for a CPU of family 6, model
37=0x25, and stepping 2 (which according to /proc/cpuinfo is the CPU I
have in my laptop, for example). These files already exist and are very
small.

> I have used a tool called 'iucode-tool' to convert the Intel
> distribution files to the blob binary file (I decided to name it
> microcode.bin and that's what I use in the module line above). This tool
> has a number of options that allow to include only those parts of the
> microcode patches that are required for your specific CPU model (it is
> able to scan for your CPU or you can provide the model as a command line
> argument)

To include only the microcode for my CPU, I have to use the -S option of
iucode-tool, right?

> Your best bet is to check whether your distribution offers iucode-tool
> and install it. Failing this you can also download the source and
> compile it (I had to do this for gentoo) - that was pretty easy.

I'm using Gentoo too. I will request an ebuild for iucode-tool. Maybe I
can also convince the microcode-data maintainer to install a binary BLOB
in addition to microcode.dat (depending on some use-flag).

> Hope this helps,

You helped a lot!


Thanks,
  Sven

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