As far as them being applied, yes. The loaded microcode is volatile.
They can kind of persist across cold reboots, but it relies on them being applied again at some point. The motherboard vendor can apply microcode updates during platform initialization before POSTing. Or they can be applied from EFI (modern equivalent of BIOS) before handing control to the kernel. Or they can be applied very early in the boot process by the kernel.
As far as them being applied, yes. The loaded microcode is volatile.
They can kind of persist across cold reboots, but it relies on them being applied again at some point. The motherboard vendor can apply microcode updates during platform initialization before POSTing. Or they can be applied from EFI (modern equivalent of BIOS) before handing control to the kernel. Or they can be applied very early in the boot process by the kernel.