On Thu, Mar 15, 2012 at 10:08:17AM -0400, Igor Mammedov wrote:
Good point. You mean we need a list of apic ids of available cpus right? Can SeaBIOS build this list by reading apic id in smp_ap_boot_code?
I've looked at how tables are build. It seems that it's not hard and sufficient to build an equivalent temporary byte array of (un)available apic ids that corresponds to 0xaf00 bitmap at boot time, under following restriction:
- apic id shall be in range [0..max_cpus)
Why this restriction? ap bootstrap code can grab array entry with atomic operation and store its apic id there.
* this will allow to allocate array where apic id will serve as index, thus making it equvivalent to 0xaf00 bitmap. * and easily fill this array in smp_ap_boot_code without inventing and using mutexes/spinlocks in smp_ap_boot_code.This will require cooperation from qemu side. apic id could be checked somewhere in device_add command handler call chain or at cpu object creation time.
Jan, What do you think about setting such restriction on apic id of cpus in qemu?
We do have such restriction currently. A couple of years ago I removed it from the kernel, but qemu and current bios code still has it.
-- Gleb.