On 12/12/2014 18:30, Dr. David Alan Gilbert wrote: > OK, let me just check that I get this.... > > It gets reset to 0 already in kvm_apic_realize
(before this patch -- after this patch it's only done in reset) > then we do the common init Then as part of starting up auxiliary processors we send an INIT interrupt, that resets the APIC and... > that sets it to !bsp - so 1 for most CPUs > then you're adding this so that a specific APIC implementation (kvm) > can nobble it back to 0 again? Yes. That's needed because this APIC implementation does not use the field at all. > and on the load side it's forced to zero by apic_pre_load. Yes. That's the common case for the !APIC implementation because it gets to zero as soon as te OS starts. Paolo
