Re: [9fans] IRQs again...

[Ronald G Minnich <rminnich@lanl.gov>]

On Mon, 27 May 2002, David Gordon Hogan wrote:

> I would like to suggest that since LinuxBios has "BIOS" in
> the name, that it should allocate IRQs to the various devices
> as part of system initialisation, as this appears to be one of
> the (de facto) jobs of the BIOS.  Every other BIOS does it.

No. Sorry. There are good reasons for this and it ain't going to happen.
We've been over this ground quite a bit over the last 2 years. The OS has
a way better idea of what it needs, and once you start pulling in nonsense
like SMP and APIC and IO-APIC it gets very very messy. The odds that the
BIOS can get things set up right for the OS become vanishingly small.

I'm still a little lost on how you plan to handle the hot plug thing. What
do you plan to do if the device is not there until after the OS boots? Or
goes away? do you reclaim the interrupt or not? Do you plan to callback to
the BIOS? We don't do callbacks either.

Of course Andrey might force me to change my mind.

> We've thought about what it would take to make Plan 9
> do this instead, and generally reached the conclusion
> that it would be a Bad Thing.

can you elaborate?

I just don't agree, and neither (it seems) do the other open source OSes
out there. But I've been wrong lots of times so if you have a solid reason
I'm all ears.

ron