linux-kernel - Re: x2APIC and many-APIC systems...

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Message-ID: <1331680589.18900.76.camel@sbsiddha-desk.sc.intel.com>
Date:	Tue, 13 Mar 2012 16:16:29 -0700
From:	Suresh Siddha <suresh.b.siddha@...el.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Daniel J Blueman <daniel@...ascale-asia.com>,
	Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, x86@...nel.org,
	Steffen Persvold <sp@...ascale.com>
Subject: Re: x2APIC and many-APIC systems...

On Tue, 2012-03-13 at 15:58 -0700, Yinghai Lu wrote:
> On Tue, Mar 13, 2012 at 2:29 AM, Daniel J Blueman
> <daniel@...ascale-asia.com> wrote:
> > Ingo, Suresh,
> >
> > Commit a35fd28256e7736cc84af8931a16224f0bfaaf6c prevents x2APIC structures
> > being used from the ACPI MADT if the cores don't advertise the x2APIC
> > feature. Commit c284b42abadbb22083bfde24d308899c08d44ffa prevents onlining
> > cores with APIC ID >255 in non-x2APIC mode. Since NumaChip/NumaConnect uses
> > x2APIC structures to describe non-x2APIC systems (AMD Opteron) with lots of
> > APICs, we thus now can't boot all the cores.
> >
> > We are able to set the x2APIC bit in the processor feature flags, so get
> > caught by the second patch. Is there an appropriate approach to use in these
> > circumstances? Otherwise, would a patch that separates the APIC ID handover
> > and future x2APIC MSR access be appropriate?
> >
> 
> add is_apicid_valid() in struct apic?

Yes, we can generalize that and move into the apicdriver. Daniel, will
you be able to prepare such a patch?

thanks,
suresh

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