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From: Andi Kleen <andi@firstfloor.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jones <davej@redhat.com>,
	x86@kernel.org, Andi Kleen <andi@firstfloor.org>,
	Arjan van de Ven <arjan@infradead.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: RFC: Bogus setting of CONSTANT TSC ?
Date: Sun, 13 Mar 2011 18:06:32 +0100	[thread overview]
Message-ID: <20110313170632.GK2499@one.firstfloor.org> (raw)
In-Reply-To: <alpine.LFD.2.00.1103121851390.2787@localhost6.localdomain6>

> This was initially introduced with commit 39b3a7 ([PATCH] i386/x86-64:
> Generalize X86_FEATURE_CONSTANT_TSC flag), though the changelog is
> utterly useless. Andi ??

Only Nehalem and beyond set the 8000_0007 flag, but Intel has had a constant
TSC since Yonah. That is what this logic implements.

However on Nehalem and beyond if the 8000_0007 is clear the BIOS wants
to tell us that it knows the system doesn't have a synchronized TSC.
This is currently still broken, but the timer watchdog usually catches
it later. It only affects a few relatively obscure systems.

-Andi

      reply	other threads:[~2011-03-13 17:06 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-11 21:24 RFC: Bogus setting of CONSTANT TSC ? Dave Jones
2011-03-12 18:58 ` Thomas Gleixner
2011-03-13 17:06   ` Andi Kleen [this message]

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