linux-kernel - Re: [PATCH -tip] x86: do_boot_cpu

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Date:	Wed, 22 Oct 2008 18:52:38 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Glauber Costa <glommer@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Maciej W. Rozycki" <macro@...ux-mips.org>,
	Max Kellermann <mk@...all.com>
Subject: Re: [PATCH -tip] x86: do_boot_cpu - check if we have ESR register

[Ingo Molnar - Wed, Oct 22, 2008 at 04:23:12PM +0200]
| 
| * Cyrill Gorcunov <gorcunov@...il.com> wrote:
| 
| > | > -		apic_write(APIC_ESR, 0);
| > | > -		apic_read(APIC_ESR);
| > | > +		if (APIC_INTEGRATED(apic_version[phys_apicid])) {
| > | > +			apic_write(APIC_ESR, 0);
| > | > +			apic_read(APIC_ESR);
| > | > +		}
| > | 
| > | i'm wondering - is the server there really that old, that it has no 
| > | integrated lapic? I.e. it's an i486 SMP box or so? Or perhaps some 
| > | other, weird SMP box?
| > | 
| > | 	Ingo
| > | 
| > 
| > I was quite wondering too -- it's Xeon server.
| > 
| > >From http://lkml.org/lkml/2008/10/20/34
| > >> Hardware: Compaq P4 Xeon server, Broadcom CMIC-WS / CIOB-X2 board.
| > >> Tell me if you need more detailed information.
| 
| ah, Compaq - how many CPUs does that box support? If it's 8 or more then 
| perhaps they turned off the real local APIC, fudged some chipset glue to 
| emulate APIC functionality and thus were able to use 8 or more of these 
| chips? The built-in lapic would only go up to 4 CPUs. (or maybe even 
| just up to dual, depending on the model)

I have no glue how many cpus it does supposrt :) Maybe Max know.

| 
| This reminds us that all the is-integrated-lapic checks still matter 
| today.
| 
| 	Ingo
| 
		- Cyrill -
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