Date: Wed, 15 Jan 1997 10:28:55 -0700 From: Steve Passe <smp@csn.net> To: Matt Thomas <matt@lkg.dec.com> Cc: smp@freebsd.org Subject: Re: Adaptec 3940UW and SMP Message-ID: <199701151728.KAA04559@clem.systemsix.com> In-Reply-To: Your message of "Wed, 15 Jan 1997 10:59:14 GMT." <199701151059.KAA24754@whydos.lkg.dec.com>
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> > What is happening is a limitation of the PCI code. Each PCI slot has > four interrupt lines (INTA .. INTD) and then are normally mapped into > ISA IRQs. Since most PCI devices only use INTA, since means there is > a simple one-to-one mapping. > > Introducing a PCI-PCI bridge means that INTB .. INTD will also be used. > Devices behind the PPB get their INT lines rotated. This rotation is > simple (take the device number, add it to the INTx, and AND with 3. > 0=INTA 3=INTD). So ahc1 is using INTB and the PCI/APIC needs to how > to map this INTB line into the APIC irq. I don't get to map anything, the MB manufacturer does that, I can only read the MP table and use what it gives me. The MP table in question shows no mapping for the ahc0/1 so they remain redirected thru the ISA bus. Ie, I am expecting them to appear on the same vector levels on the APIC as they appear on the 8259s. Could you expand on how the INTA/B/C/D lines are handled when redirected via the ISA bus? Specifically, how does the ahc1 INTB line get tied to the ISA INT line in a normal setup? -- Steve Passe | powered by smp@csn.net | FreeBSD
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