linux-kernel - Re: [RFC PATCH 2/4] x86: use dmi check to treat disabled cpus as hotplug cpus.

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Message-ID: <86802c441001121119sc779437if93fbbb81482c48f@mail.gmail.com>
Date:	Tue, 12 Jan 2010 11:19:25 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"ananth@...ibm.com" <ananth@...ibm.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 2/4] x86: use dmi check to treat disabled cpus as 
	hotplug cpus.

On Tue, Jan 12, 2010 at 10:24 AM, Suresh Siddha
<suresh.b.siddha@...el.com> wrote:
> On Tue, 2010-01-12 at 10:13 -0800, Yinghai Lu wrote:
>> ok let stay with option 1.
>>
>> and would like to use DMI to blacklist those systems that do need treat disabled
>> cpus MADT as hotplug cpus.
>
> Yinghai, I don't think we have to worry about disabled cpu's etc using
> DMI etc. If we really come across such a system, they can use ACPI FADT
> flags (ACPI_FADT_APIC_PHYSICAL) to specify that they need to use
> physical mode.

i want other way.

1. after use nr_cpu_ids instead of num_processors to decide if we need
switch to physflat.
some systems that disabled cpus entries that will use physflat even
those system doesn't support
CPU hotplug and could use logical flat.
2. those systems are several model (2 sockets or 4 sockets or 8
sockets) but share one BIOS, and BIOS guys are
 too lazy to remove the disabled entries.
3. so I want to use DMI list to state that those system doesn't need
to treat those disabled cpu as hot plug cpu.
   then we could use logical flat with them.

YH
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