Date: Sun, 6 Nov 2005 10:12:55 -0500 From: John Baldwin <jhb@FreeBSD.org> To: Vaibhave Agarwal <vaibhave@cs.utah.edu> Cc: freebsd-net@FreeBSD.org, current@FreeBSD.org, chris@gnome.co.uk, chmr@edvz.tu-graz.ac.at Subject: Re: Freebsd 6.0 doesnt detect local APIC on a Pentium 3 machine Message-ID: <200511061012.57212.jhb@FreeBSD.org> In-Reply-To: <Pine.LNX.4.61.0511060450130.4600@trust.cs.utah.edu> References: <20051027233636.GA39380@dmw.hopto.org> <Pine.LNX.4.61.0510281621120.19263@trust.cs.utah.edu> <Pine.LNX.4.61.0511060450130.4600@trust.cs.utah.edu>
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On Sunday 06 November 2005 07:06 am, Vaibhave Agarwal wrote: > hi, > > FreeBSD 6.0 always uses local APIC for the clock. > > But on my Pentium 3, 850 MHz machine, it doesnt detect local APIC and > falls back to using the motherboard clock for the clock interrupts. > > I figured this out by printing the value of > "using_lapic_timer" variable in the sys/i386/isa/clock.c file, > which is always 0. > > But when I use Intel's 3GHz - 64 bit Xeon processor, it detects local APIC > and all works fine. > > Can someone please tell me the reason, why local APIC doesnt work for the > Pentium 3 machines ? Or is there a way to fix this ? We don't detect the local APIC via MSR's or the APIC bit in cpu_features, but rely on a working MP Table or MADT table to setup both the local APIC(s) and I/O APIC(s). Does your machine have a valid MP Table or an APIC table in its acpidump? Many UP machine BIOSes don't include those tables. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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