Hello Dimitri,
The source of this is that the linux-aws (and some other cloud-specific)
kernels do not have CONFIG_MICROCODE_OLD_INTERFACE enabled, while they
are enabled in the generic kernel configs.
For consideration, this is the kernel config documentation for this
option:
config MICROCODE_OLD_INTERFACE
bool "Ancient loading interface (DEPRECATED)"
default n
depends on MICROCODE
---help---
DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
which was used by userspace tools like iucode_tool and microcode.ctl.
It is inadequate because it runs too late to be able to properly
load microcode on a machine and it needs special tools. Instead, you
should've switched to the early loading method with the initrd or
builtin microcode by now: Documentation/x86/microcode.rst
I'm going to mark this issue public. Thanks.
** Information type changed from Private Security to Public Security
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Packages, which is subscribed to linux-aws in Ubuntu.
https://bugs.launchpad.net/bugs/1863299
Title:
linux-aws fails to late load microcode, works with generic
Status in linux-aws package in Ubuntu:
New
Bug description:
[Impact]
* Late loading of intel microcode doesn't seem to work on aws.
[Test Case]
* Boot Focal on AWS metal instance
* Install intel-microcode package
* Disable early microcode loading:
sudo rm /usr/share/initramfs-tools/hooks/intel_microcode to disable
including microcde in the initrd
* Update initrd
sudo update-initramfs -u
* Observe that late loading (due to /usr/lib/tmpfiles.d/intel-microcode.conf
) does not happen.
I.e. expected to see something like this:
$ journalctl -b | grep microcode
Feb 14 11:08:38 ottawa kernel: microcode: sig=0x506e3, pf=0x20, revision=0xc6
Feb 14 11:08:38 ottawa kernel: microcode: Microcode Update Driver: v2.2.
Feb 14 11:08:42 ottawa kernel: microcode: updated to revision 0xd6, date =
2019-10-03
Feb 14 11:08:42 ottawa kernel: x86/CPU: CPU features have changed after
loading microcode, but might not take effect.
Feb 14 11:08:42 ottawa kernel: microcode: Reload completed, microcode
revision: 0xd6
instead I see something like this:
Feb 14 11:08:38 ottawa kernel: microcode: sig=0x506e3, pf=0x20, revision=0xc6
Feb 14 11:08:38 ottawa kernel: microcode: Microcode Update Driver: v2.2.
(no updated to revivsion .... message)
[Regression Potential]
* Late loading is new, as the current default is to load microcode
early from initrd. It will only change behaviour on initrd-less
bionic-minimal images, and any image types on later releases, but only
when booted on the .metal instances.
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