Date: Mon, 7 Nov 2005 18:38:00 -0700 (MST) From: Vaibhave Agarwal <vaibhave@cs.utah.edu> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-net@freebsd.org, freebsd-acpi@freebsd.org, current@freebsd.org, Nate Lawson <nate@root.org> Subject: Re: Freebsd 6.0 doesnt detect local APIC on a Pentium 3 machine Message-ID: <Pine.LNX.4.61.0511071830570.4600@trust.cs.utah.edu> In-Reply-To: <200511071105.58729.jhb@freebsd.org> References: <20051027233636.GA39380@dmw.hopto.org> <Pine.LNX.4.61.0511061525330.16649@trust.cs.utah.edu> <436E874E.4010305@root.org> <200511071105.58729.jhb@freebsd.org>
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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
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