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Date: Wed, 13 Nov 2002 17:38:05 -0800 (PST)
From: Linus Torvalds <torvalds@transmeta.com>
To: "Nakajima, Jun" <jun.nakajima@intel.com>
cc: linux-kernel@vger.kernel.org
Subject: RE: local APIC may cause XFree86 hang
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On Wed, 13 Nov 2002, Nakajima, Jun wrote:
> 
> The one instance I saw was that the BIOS was reading 8254 in a tight loop
> for a calibration purpose, and it was assuming the time proceeded in a
> constant speed, to exit the loop. In other words, it never assumed it could
> get interrupts. To vm86, interrupts are invisible, but they have impacts on
> the actual speed. 

That sound slike a perfectly ok thing to do - apart from the hw latching
which might confuse the kernel.

When enabling the local APIC, Linux doesn't actually disable legacy PIT
interrupts, so again I don't really see what the apparent connection
between the hang and the APIC is. So I'd still suspect it's more
timing-related than anything else.

		Linus

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