Messages in this thread | | | Date | Sun, 31 Aug 2014 16:45:48 -0300 | From | Henrique de Moraes Holschuh <> | Subject | early microcode: how to disable at runtime? |
| |
Currently, there is no way to disable early microcode update at runtime. If an early initramfs with microcode update data is available, it will always be used.
This can be a very big deal when things go wrong: it is hard for the regular user to recover from an initramfs image that crashes the system, and the early initramfs has no "disable" trigger.
In the general case, booting from rescue media will be required to fix the system.
Unfortunately, the BSP microcode update is handled before early_param() is available, so a kernel command line parameter to disable early microcode updates for the BSP isn't easily possible.
Other than duplicating much of the code in parse_early_param/parse_args to search for a "noearlymcu" parameter, is there any other way we could add a disable switch for the early microcode update system?
Otherwise, distros will have to generate a rescue initramfs image automatically that has the entire early initramfs stripped, or somehow get the bootloaders (and mkinitramfs/dracut) to deal (correctly) with two initramfs images.
-- "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
| |