Hello, I've just stumbled across this commit, and I'm wondering if that's actually correct (I too have at least one system where such IDs are reported in MADT): For offline/absent CPUs, the firmware may not know the APIC IDs at the point MADT is built, so I think it is quite reasonable to put ~0 in there. The ACPID spec specifically calls out that the IDs must not change across sleep states, which implies to me that they may change across an offline period of a CPU. IOW I think such entries still need to contribute to the count of disabled CPUs.
I notice a similar change has been done for the xAPIC case a while ago by you, Thomas. Jan
