Re: Hot PCI bus plugging

Wakko Warner (wakko@animx.eu.org)
Wed, 24 Nov 1999 12:49:30 -0500

> > Looks like noone brought up the subject of resource allocation, so I will.
> > I don't know much about the bios and PCI as far as this goes, but doesn't
> > the bios assign io/mem/irq at boot up? How would this work on hot plug pci?
> > Who or what assigns the resources?
>
> Yes you have a very good point there, that I mentioned in a private
> e-mail. The BIOS does that at bootup, so we would have to assume
> control of that ourselves. That wouldn't be too difficult, but would
> add some housekeeping to the PCI layers -- mainly allocating and keeping
> track of IRQs and base addresses/ranges. We also have to be careful
> to make sure we don't share IRQs with devices that don't want to share
> them -- introducing the possibility the user could insert a card that
> can't get an IRQ (ouch) because there are none available. (Dang those
> broken cards that don't share.. Why doesn't everybody just read the
> friggin' PCI spec??? :) )

Also speaking of that, what about systems that actually put pci devices on
irq 16+? I've seen some (NT hated it, linux didn't care <eg> It was a
supermicro dual ppro) board do it like the one I just meantioned. I believe
some tyan boards (like the one I have, but mine doesn't allocate higher than
15) do it as well.

I wasn't aware that some pci devices don't like sharing IRQs. I didn't
think it mattered.

-- 
 Lab tests show that use of micro$oft causes cancer in lab animals


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