Re: bogus MADT X2APIC entry [Re: illegal instruction in kernel at boot]

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sun, Sep 29, 2024 at 12:35:32AM +0900, Rin Okuyama wrote:
> Hi,
> 
> This thread?
> 
> https://mail-index.netbsd.org/port-amd64/2023/12/30/msg003666.html

Yes that's it. I didn't look back enough.

The complete sentence from the latest ACPI spec is:
"On some legacy OSes, Logical processors with APIC ID values less than 255 (whether in XAPIC or X2APIC mode) must use the Processor Local APIC structure to convey their APIC information to OSPM, and those processors must be declared in the DSDT using the Processor() keyword. Logical processors with APIC ID values 255 and greater must use the Processor Local x2APIC structure and be declared using the Device() keyword."

To me this doens't means that the OS has to reject X2APICs with ID < 255.
It also doesn't prevent an APCI implementation from using X2APICs with low
IDs if it doens't care about legacy OSes.

I am reading it wrong ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--