Date: Tue, 06 Dec 2005 15:59:34 -0800 From: Julian Elischer <julian@elischer.org> To: Jack Vogel <jfvogel@gmail.com> Cc: current@freebsd.org Subject: Re: can someone explain...[ PCI interrupts] Message-ID: <439625E6.1000104@elischer.org> In-Reply-To: <2a41acea0512061513l10695474yc63df81c5c92fe8f@mail.gmail.com> References: <43961758.4020407@elischer.org> <2a41acea0512061513l10695474yc63df81c5c92fe8f@mail.gmail.com>
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Jack Vogel wrote: >On 12/6/05, Julian Elischer <julian@elischer.org> wrote: > > >>In short words for the likes of me, >>Can someone give a quicj roundup on PCI routing in 4.x and -current. >> >>Specifically: >> >>How much is set up by the BIOS and how much is set up by the OS (4.x and >>-current). >> >>How much of my fondly held knowledge of the old hardware PICS (where >>an interrupt corresponded to an interrupt line) is now out of date? >> >>In this world of multiple PCI to PCI bridges, how much latitude doe the >>OS have in >>deciding where an interrupt turns up? >>(in 4.x and -current) >> >>An example is my Dell PE2850 (on 4.x), in which my 4 port ethernet card >>seems to >>be assigned irqs 10,14,14,2 in that order sometimes and 16,17,17,2 at >>others. >> >>Who is making those decisions? Is it the BIOS and 4.x is just playing along? >> >>Assuming the much maligned "boot interrupt" comes in on irq2, does the OS >>have the oportunity to put my 4th port somewhere else? On 4.x it collides >>with one of my ether ports but in -current it doesn't >> >>Linux and -current on teh same box a;;ocate way different irqs, and >>they agree about it.. i.e. Linux and -current assign my 4 port card IRQs >>18,19,19,16. >> >>Do they agree becasue something else has decided it (the bios again?) or >>becasue they >>use the same algorythm to work it out.. >> >>Also, if the "boot interrupt" was previously set to 2, is that likely to >>have changed in -current? >>Am I now going to get clobbered on IRQ16? If yes, is this something >>that teh BIOS writers >>decided, or something that the Motherboard designers decided? >> >> > >The canonical method for getting this kind of information now (and at >least current Linux kernels do this unless forced not to) is via ACPI... >And indirectly that really means how the BIOS sets up its tables. > >I'm still coming up to speed on the current FreeBSD kernel, but I >would hope it does the same :) > > so, for your next trick can you explain acpi and the "boot interrupt" :-) p.s. got info on the dewey beach card yet? ;-) (That's what's causing me this pain :-) >Cheers, > >Jack > >
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