Date: Tue, 19 Nov 1996 14:04:52 -0700 From: Steve Passe <smp@csn.net> To: "J.M. Chuang" <smp@bluenose.na.tuns.ca> Cc: smp@freebsd.org Subject: Re: Tyan Tomcat III (S1563D) Message-ID: <199611192104.OAA19927@clem.systemsix.com> In-Reply-To: Your message of "Mon, 18 Nov 1996 09:37:31 -0400." <199611181337.JAA15924@bluenose.na.tuns.ca>
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Hi, I think we have a new class of "not connected" INTs for the IO APIC. Jim Chuang was testing the APIC_IO option to the SMP kernel (thanx Jim), and found the following problem: --- > Jim wrote: >>> >wd0: interrupt timeout: >>> >wd0: status 58 <rdy, seekdone, drq> erro 0 >>> ... --- > I (smp) replied: >I guess I need to look at the chipsets to see how the IDE INTs are routed. >Since these are on a motherboard chipset, they might now get "off the chip" >and thus are not available to route to the APIC chip. This is a common >problem with EISA chipsets and the system timer, as both timer and 8259 ICUs >are on the same chip, and they didn't think there would ever be a need >to bring the line off the chip. > >-- >thanx for replying, I will get back to you when I have thought it over >a bit... --- so I looked at the chipset, specifically the 82371SB (aka PIIX3) and am currently of the opinion that the chip directly routes interrupts from the IDE controller core to INTs 14/15 on the 8259 core. The datasheet lists INTs 14/15 as INPUTS ONLY, and I cannot find any other pin on the chip that would bring IDE INTs off-chip. If I am correct this means that the IO APIC (which is on a separate piece of silicon) cannot service IDE INTs with this hardware. This chip is used in both the Natoma and Triton-II (Triton-I?) chip sets. Whether this affects other sets like Neptune is unknown to me at this point, but I would guess it does. The implication of this is that we will probably never support IDE drives in the SMP kernel with APIC_IO mode enabled on these chipsets. "mixed-mode" programming might be possible, but IMHO, would BLOW CHUNKS! -- Steve Passe | powered by smp@csn.net | FreeBSD -----BEGIN PGP PUBLIC KEY BLOCK----- Version: 2.6.2 mQCNAzHe7tEAAAEEAM274wAEEdP+grIrV6UtBt54FB5ufifFRA5ujzflrvlF8aoE 04it5BsUPFi3jJLfvOQeydbegexspPXL6kUejYt2OeptHuroIVW5+y2M2naTwqtX WVGeBP6s2q/fPPAS+g+sNZCpVBTbuinKa/C4Q6HJ++M9AyzIq5EuvO0a8Rr9AAUR tBlTdGV2ZSBQYXNzZSA8c21wQGNzbi5uZXQ+ =ds99 -----END PGP PUBLIC KEY BLOCK-----
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