RE: local APIC may cause XFree86 hang

[Linus Torvalds]

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