Date: Wed, 15 Jan 1997 10:00:45 -0700 From: Steve Passe <smp@csn.net> To: Rob Schofield <rschof@mccomm.nl> Cc: freebsd-smp@freebsd.org Subject: Re: Motherboard & ChipSet pointers? Message-ID: <199701151700.KAA04351@clem.systemsix.com> In-Reply-To: Your message of "Wed, 15 Jan 1997 12:57:01 %2B0700." <199701151157.MAA00873@mccomm.nl>
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> > EISA should be avoided for SMP/technical reasons (which I have gone into > > in detail in the past). I highly recommend the Gigabyte GA586DX if > > you want a P5 system. P6 is an unknown to me. > > Steve, can you briefly re-hash these for me, or point me at a doc I > can look at? This is worrying as I have picked up an EISA-based server > expressly to run BSD! > > Any info gratefully received. Some EISA systems do not connect the system clock (8254) to the IO APIC.This requires "mixed-mode" programming the IO APIC AND the 8259 ICU. I have already written the code to do this and it appears to work. BUT this is a small in-efficiency for hard-clock INTs. So far ALL EISA systems I have seen use the ISA INTs 0-15 redirection capability for routing both EISA AND PCI INTs to the lower 16 ISA INT vectors. some (majority, but NOT all) PCI/ISA systems route the PCI INTs to upper (ie above 16) IO APIC INTs, thus giving you 4 or more extra INT vectors, helping greatly with the typical "not enough INT choices" on the ISA bus. this fact is the major reason I have for avoiding EISA boards. you need to go thru the mptable database to see details about what I am talking about here. -- 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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