On Wed, 2017-03-22 at 04:43 -0400, Paolo Bonzini wrote: > > Understood---my question is how you would set up the alternate > boot order: is it something like "keep a button pressed while > turning on", or something written in NVRAM, or something else > that is completely different?
In my case the real hardware has a management processor on the board and the temporary boot source (and also the permanent one for that matter) for the main processor can be set from there. Since neither the BIOS nor the management firmware are open source, I don't know how it technically works, but I assume there either is some shared memory between the main BIOS and the management processor or alternatively the BIOS talks with the management processor with some protocol during boot to get the order.