Re: Freebsd 6.0 doesnt detect local APIC on a Pentium 3 machine

From: Vaibhave Agarwal <vaibhave_at_cs.utah.edu>
Date: Mon, 7 Nov 2005 18:38:00 -0700 (MST)
On Mon, 7 Nov 2005, John Baldwin wrote:

> And even then it can't be used for any device interrupts since there aren't 
> any I/O APICs.  On a UP machine without I/O APICs, it's actually probably 
> more optimal to just use irq0 and irq8 for clocks rather than the lapic timer 
> anyway.  The only real possible gain is the ability to use the profiling 
> interrupt from the local APIC.

I got access to the BIOS of the Pentium 3 machine I am using, but it has 
no option to enable/disable the local APIC.

Joseph Koshy is right, Linux enables the local APIC timer while booting 
up. I got the following in the bootup log of Linux 2.4 kernel on the same 
machine.

-------------------------
Local APIC disabled by BIOS -- reenabling.
Found and enabled local APIC!

Using local APIC timer interrupts. 
calibrating APIC timer ...
-------------------------

Though there is no I/O apic in the UP machines, but I only wanted to use 
local APIC timer in the lapic_timer_oneshot() mode to schedule few timers 
accurately.

thanks
vaibhave
Received on Tue Nov 08 2005 - 00:38:02 UTC

This archive was generated by hypermail 2.4.0 : Wed May 19 2021 - 11:38:47 UTC