Re: APIC version and 8-bit APIC IDs

From: Martin Wilck
Date: Mon Aug 29 2005 - 02:26:30 EST


Maciej W. Rozycki wrote:

You are unfortunately mistaken -- the spec is explicit about *local* APIC IDs having to start at 0. There are at least two places in the spec that refer to that.

I see. Thanks for the clarification.

You can always assign 0, 16, 17, etc. to local APICs and then 1, 2, 3, etc. for I/O APICs.

Actually, that's what we did (I messed thinks up in my posting). I think that's an ugly configuration, though, and totally misleading in terms of system topology.

Frankly I don't know what the actual justification behind the requirement is. Note that the ID of 0 need not necessarily belong to the BSP.

Starting both local APICs and IO-APICs at 0 isa working and aesthetically pleasing solution. We're pursuing that now.

Thanks again, Martin

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