linux-kernel - Re: [PATCH 2/6] x86: apic

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Date:	Mon, 18 Aug 2008 18:39:43 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	Arjan van de Ven <arjan@...radead.org>, mingo@...e.hu,
	hpa@...or.com, tglx@...utronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] x86: apic - unify lapic_resume

[Maciej W. Rozycki - Mon, Aug 18, 2008 at 03:19:05PM +0100]
| On Sun, 17 Aug 2008, Cyrill Gorcunov wrote:
| 
| > it seems this limit is not APIC related since iirc 82489DX allows
| > to address 2^14 bits, x2APIC - more then 128 entities too. So I suspect
| > it somehow cpu bitmap related. Am I wrong (I didn't _check_ the code)?
| 
|  For the record: the 82489DX supports an 8-bit physical unit ID so 256
| distinct values are supported.  Of these I gather 255 is taken for the
| broadcast ID in the physical destination mode, but that is nowhere
| explicitly confirmed in the 82489DX docs (it can be implied from protocol
| description though).  While the ID is indeed 8-bit in the 82489DX, for
| systems where future compatibility was a concern Intel recommended the use
| of IDs from 0 through to 14 only in anticipation of the future integrated
| APIC with the physical mode addressing capability limited to 4 bits only
| (and 15 taken for the broadcast ID).
| 
|  Full 32 bits are available with the 82489DX for the logical destination 
| mode and only the flat (no cluster) mode is supported.
| 
|   Maciej
| 

Thanks, Maciej! The doc says to use 0-14 so I misinterpreted it as
bits :(. I've to be more carefull next time. Thanks!

		- Cyrill -
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