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You can only upgrade microcode on any given boot, not downgrade it. Therefore, if the BIOS has already upgraded your microcode for you on boot, you can't undo t

You can only upgrade microcode on any given boot, not downgrade it. Therefore, if the BIOS has already upgraded your microcode for you on boot, you can't undo that from the OS.

qayxc 5y ago
I misread that there, so disregard the first reply. Point still stands: no one forces you to upgrade your BIOS (unless there's problems) and even then, patching the BIOS upgrade itself is still an option. So it remains under user control.
qayxc 5y ago
The BIOS doesn't upgrade microcode - the OS does. During boot there's usually no network connectivity, so how would the BIOS even know of an update, let alone acquire it?
- tomxor 5y ago
  They both have the opportunity to upgrade it. The BIOS holds a copy of the microcode and this can be upgraded by upgrading the BIOS/EFI (bundled with BIOS updates). The same for the OS. On boot the BIOS loads it's update first, then the OS, provided each is newer than the currently loaded microcode. So the idea is that if you don't like this update, you need to prevent your BIOS from updating (or downgrade it), and then also configure Linux to ether not upload it's microcode, or load a specific one.
- marcan_42 5y ago
  The BIOS itself comes with microcode. You upgrade your BIOS for whatever reason and it comes with new microcode applied on boot, which you can't disable. Sure, if you don't upgrade your BIOS you can keep using the old microcode. But you might have to to fix bugs or improve performance.
- numpad0 5y ago
  Common misconception about Intel microcode ROM is it's some sort of Flash memory, it's not. Update vaporizes each reset and the same "update" is loaded on each bootup.
- 323 5y ago
  It's explained in the article. You update your BIOS to get better DDR5 compatibility, but the new BIOS will also include a microcode update.
- zokier 5y ago
  The CPU can update its microcode before executing BIOS, the BIOS can do its updates, and then the OS can do its stuff. It's all described in https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/best-practices/microcode-update-guidance.html https://www.intel.com/content/www/us/en/developer/articles/t...
  - qayxc 5y ago
    That just when the update is applied, not how it gets there. The FIT is still updated externally (e.g. by the OS) and doesn't magically fill itself with new microcode.
- deleted 5y ago
  [deleted]

You can only upgrade microcode on any given boot, not downgrade it. Therefore, if the BIOS has already upgraded your microcode for you on boot, you can't undo that from the OS.

qayxc 5y ago

I misread that there, so disregard the first reply. Point still stands: no one forces you to upgrade your BIOS (unless there's problems) and even then, patching the BIOS upgrade itself is still an option. So it remains under user control.

qayxc 5y ago

The BIOS doesn't upgrade microcode - the OS does. During boot there's usually no network connectivity, so how would the BIOS even know of an update, let alone acquire it?

tomxor 5y ago
They both have the opportunity to upgrade it. The BIOS holds a copy of the microcode and this can be upgraded by upgrading the BIOS/EFI (bundled with BIOS updates). The same for the OS. On boot the BIOS loads it's update first, then the OS, provided each is newer than the currently loaded microcode. So the idea is that if you don't like this update, you need to prevent your BIOS from updating (or downgrade it), and then also configure Linux to ether not upload it's microcode, or load a specific one.
marcan_42 5y ago
The BIOS itself comes with microcode. You upgrade your BIOS for whatever reason and it comes with new microcode applied on boot, which you can't disable. Sure, if you don't upgrade your BIOS you can keep using the old microcode. But you might have to to fix bugs or improve performance.
numpad0 5y ago
Common misconception about Intel microcode ROM is it's some sort of Flash memory, it's not. Update vaporizes each reset and the same "update" is loaded on each bootup.
323 5y ago
It's explained in the article. You update your BIOS to get better DDR5 compatibility, but the new BIOS will also include a microcode update.
zokier 5y ago
The CPU can update its microcode before executing BIOS, the BIOS can do its updates, and then the OS can do its stuff. It's all described in https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/best-practices/microcode-update-guidance.html https://www.intel.com/content/www/us/en/developer/articles/t...
- qayxc 5y ago
  That just when the update is applied, not how it gets there. The FIT is still updated externally (e.g. by the OS) and doesn't magically fill itself with new microcode.
deleted 5y ago
[deleted]