Date: Wed, 04 Jun 1997 22:53:50 +0800 From: Peter Wemm <peter@spinner.dialix.com.au> To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: smp@FreeBSD.ORG Subject: Re: Supermicro SMP boards? Message-ID: <199706041453.WAA18319@spinner.dialix.com.au> In-Reply-To: Your message of "Thu, 05 Jun 1997 00:10:29 %2B0930." <199706041440.AAA15900@genesis.atrad.adelaide.edu.au>
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Michael Smith wrote: > > G'day; in brief, I've been offered a Supermicro board (either a P6*E > or F, it's not immediately clear), for around AUD$300 (US$240). > > I've been toying with the idea of building a new machine, and an SMP > box sounds like a lot of fun. Is this a bearable price? Is the board > a goer, or a lemon? (yes, I've noted the two are listed on the SMP > pages) > > Any other suggestions while I'm at it? Ta! The only thing that I'm aware of is that the timer0 (the 100Hz timer) is only connected to the 8259 pic emulation and doesn't reach the IO apic. The PIIX3 seems to have a design choice where it's possible to reuse the pin that would be the irq0 output to the IO apic instead as a steerable motherboard interrupt, eg from the second IDE. It's possible to reprogram this in the piix3, but from my understandingm this is a motherboard design issue and not something we can get away with. However, the SuperMicro board in question does have a workaround, see the option SMP_TIMER_NC, where the 8259 is set up so that it provides a daisy chained interrupt to the IO apic, and we treat that as an IRQ0. This works for only one interrupt though since there's no way to tell which irq on the 8259 triggered the apic. (only the input for the irq0 is unmasked on the 8259 so it doesn't matter). In the SMP-GENERIC file: # SuperMicro P6DNxxx: #options SMP_TIMER_NC # 8254 NOT connected to APIC I don't know if this is the same board, but could be. > -- > ]] Mike Smith, Software Engineer msmith@gsoft.com.au [[ > ]] Genesis Software genesis@gsoft.com.au [[ > ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ > ]] realtime instrument control. (ph) +61-8-8267-3493 [[ > ]] Unix hardware collector. "Where are your PEZ?" The Tick [[ Cheers, -Peter
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