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From: Cyrill Gorcunov <gorcunov@gmail.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>,
	Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
	Yinghai Lu <yinghai@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC -tip] x86,apic -- reduce disable_apic usage
Date: Sun, 5 Jul 2009 23:02:11 +0400	[thread overview]
Message-ID: <20090705190211.GK4791@lenovo> (raw)
In-Reply-To: <4A50E323.6060109@zytor.com>

[H. Peter Anvin - Sun, Jul 05, 2009 at 10:30:11AM -0700]
| Maciej W. Rozycki wrote:
| > 
| >  How do you set cpu_has_apic for systems with discrete local APICs?  The 
| > CPUID flag is not set in this case.
| > 
| 
| Well, should it be?  We do set flags when they're appropriate to us, and
| if the semantics are such as that is inappropriate we can set a custom bit.
| 
| 	-hpa
| 

Peter, Maciej but how kernel behaved on older cpu long time ago?

I mean -- should user pass "lapic" cmdline option too be
able to use apic functionality? (i'm asking since I just
don't know how it had been working before). Current
code (if only I'm not _missing_ something) relies on cpu_has_apic
bit. And even if MP table has been parsed and APIC base found,
cpu_has_apic could be not set so detect_init_APIC will fail
if no "lapic" option passed (in case of old cpu without this cpuid
bit produced) as we eventually stay with pic mode.

	-- Cyrill

  reply	other threads:[~2009-07-05 19:02 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-05 16:20 [RFC -tip] x86,apic -- reduce disable_apic usage Cyrill Gorcunov
2009-07-05 16:38 ` Maciej W. Rozycki
2009-07-05 16:59   ` Cyrill Gorcunov
2009-07-05 17:12     ` Cyrill Gorcunov
2009-07-05 17:17       ` Cyrill Gorcunov
2009-07-05 17:47         ` Maciej W. Rozycki
2009-07-05 18:12           ` Cyrill Gorcunov
2009-07-05 17:30   ` H. Peter Anvin
2009-07-05 19:02     ` Cyrill Gorcunov [this message]
2009-07-05 19:18       ` H. Peter Anvin
2009-07-05 19:46         ` Cyrill Gorcunov
2009-07-07 23:49     ` Maciej W. Rozycki
2009-07-08 14:44       ` Cyrill Gorcunov

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