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Re: initramfs-tools and intel-microcode with kernel 3.9.1 (sid)

On Tue, 09 Jul 2013, Klaus wrote:
> On my laptop I'm running sid amd64.
> I've noticed that during the early stages of booting, the Intel
> microcode fails to get loaded. Switching back

On 3.9.x, it should load as the very first thing the kernel actually logs
(it will be the very first line in /var/log/dmesg), and not through the
firmware loader.

> to kernel version 3.8.2 solves this issue. So far I can't tell
> whether this is an actual problem, since I haven't
> even understood what the microcode is or does.

It fixes nasty bugs in your system processor.  But it is possible that you
don't need a microcode update in the first place at this time, which would
explain why you don' get a "microcode early update" first line in

> When I manually re-run "update-initramfs -uv", it tells me that the
> microcode is found, bundled and put into
> the initrd image. Here is an extract of the output:

It does, but as an early initramfs.  And it could still be either the same
version as the microcode in your BIOS/EFI, or maybe even an older version.
In either case, it will not be used, as the kernel _never_ downgrades

> intel-microcode: Using early firmware update mode (Linux v3.9 and later)...
> /usr/sbin/iucode_tool: system has processor(s) with signature 0x0001067a
> /usr/sbin/iucode_tool: selected 3 microcode(s), 3 signature(s)

Please boot kernel 3.9 with the early initramfs, and give me the output of:

grep microcode /proc/cpuinfo

/usr/sbin/iucode_tool -s 0x0001067a -l /lib/firmware/intel-ucode/

> Also interesting (?) to see, that the newer initrd image is not compressed:

The early initramfs image is an uncompressed CPIO archive without CRC, which
is *prepended* to the regular compressed initramfs image.

There isn't an userspace tool that actually duplicates what the kernel does
for loading the initramfs image (it will read any mix of compressed and
uncompressed cpio archives appended one after the other.  However, the early
initramfs for firmware and microcode update *must* be uncompressed, and it
*must* be the first cpio image in the initramfs).

  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

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