Date: Mon, 11 Aug 1997 23:26:39 -0700 From: Chris Browning <brownie@earthling.net> To: smp@FreeBSD.ORG Subject: Re: General smp & bios questions Message-ID: <33F0021F.49BFE86@earthling.net> References: <199708120359.VAA17290@Ilsa.StevesCafe.com>
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> > My system has to I/O APIC's in it. The 2nd one is disabled > > by default in the bios. yeah, disabling the second I/O APIC is a pretty normal default. Some brain-dead OSes can't handle more than one. > > I also have an entry for 'PIC interrupt Routing', which is > > set to 'default'. The other choice is 'Through IO APIC'. Using the "Through IO APIC" allows the I/O APIC to deliever interrupts through the APIC bus. This is the prefered way of doing things. Otherwise, interrupts are "hardwired" to a particular processor. It doesn't matter too much since when the system is put into full SMP mode, you will leave whichever one you choose. Through the I/O APIC is closer to SMP :-). > > > > Does any of this ring any bells? Yes. I work with our BIOS group to help them use these features. > I've left the 2nd APIC disabled > > since I did not beleive that your code supported more than one > > of them. Now, this would be a shame. This is a major scalibility limiter. If possible, you should use the 2nd I/O APIC. Otherwise, you are losing several interrupts and are crowding the ISA compatibility interrupts unecessarily. > leave the second APIC disabled, and use "Through IO APIC" Any particular reason why? All of those extra interupts going to waste? I agree with the "Through IO APIC". Chris Not speaking for nobody.
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