Date: Thu, 07 Feb 2002 15:06:03 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: "Dorr H. Clark" <dclark@applmath.scu.edu> Cc: Igor Lepechin <gogi@themoscowtimes.com>, freebsd-smp@FreeBSD.ORG Subject: Re: Troubles with MP on ServerWorks NB6635 platform Message-ID: <3C63085B.C585BF04@mindspring.com> References: <Pine.GHP.4.21.0202071011360.25435-100000@hpux38.dc.engr.scu.edu>
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"Dorr H. Clark" wrote: > > On Mon, 4 Feb 2002, Igor Lepechin wrote: > > > Feb 4 02:44:49 web /kernel: APIC_IO: Testing 8254 interrupt delivery > > Feb 4 02:44:49 web /kernel: APIC_IO: Broken MP table detected: 8254 is not connected to IOAPIC #0 intpin 2 > > Feb 4 02:44:49 web /kernel: APIC_IO: routing 8254 via 8259 and IOAPIC #0 intpin 0 > > I've seen this on a prototype board also, > which didn't involve the ServerWorks chips. > The system otherwise appeared to function > although the testing was not extensive. > > Is it possible this is just an alarming tone > for an otherwise acceptable code path? There are two possible breakages: 1) The MP Table does not accurately reflect how the hardware works. That's its job; if it doesn't do its job, then it might as well be replaced with one that daoes (i.e. reflash your MB with a working BIOS, please) 2) The 8254 is not wired into the IO APIC correctly. This is more serious. It's either a motherboard layout flaw, or it's a chipset flaw, and it's going to take an incredible synchronization penalty to work around the problem, to the point that you are much better off with a different motherboard, since the benefit you gain from the additional processor is being spent on workarounds. In either case, the warning is telling you that you are paying a honking performance penalty, since it has to treat both cases as if the hardware is really broken. Ask the vendor if there is a BIOS update, or if their harware design is bogus (ask in that order, or you are unlikely to get a BIOS update... 8-) 8-)). -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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