On 10/22/2012 01:43 PM, Eric W. Biederman wrote: > > The reason the BIOSen go wonky is the INIT cause the cpu to go to the > reset vector at 4G-16 bytes. So it is very much expected that the > BIOSen start acting like you just came out of reset. > > If you can clear bit 8 of IA32_APIC_BASE_MSR and inform the cpu to not > send the cpu to 4G-16 bytes and instead send the cpu into it's magic > startup-ipi-wait mode then the BIOSen will not be involved on that path. > > It is a simple question of does the cpu support clearing bit 8 > meaningfully. > > If the cpu allows bit 8 to be cleared and sends the cpu to the reset > vector on receipt of the INIT IPI I would call that a deviation from the > x86 cpu specification. > > So clearing bit 8 is not a question about BIOSen it is a question of can > we avoid the BIOSen, by using an obscure under-documented cpu feature. > As I said, I thought Fenghua tried that but it didn't work, experimentally. -hpa
