Messages in this thread | | | Date | Mon, 07 Jun 2010 14:05:17 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [tip:x86/irq] x86, acpi/irq: Handle isa irqs that are not identity mapped to gsi's. |
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On 05/05/2010 02:32 AM, Eric W. Biederman wrote: >> >> can you use legacy_irq->nr_legacy_irqs instead of NR_IRQS_LEGACY ? > > No. legacy_irq->nr_legacy_irqs is just for dealing with hardware that > does not have i8259 pics. >
I don't know if it is "just" for this purpose. Quite on the contrary. In fact, the fact that NR_IRQS_LEGACY is showing up at all looks like a real problem.
> Here I am reserving 16 irqs above the gsi range in case we get a > weird gsi to isa irq mapping.
But that 16 is exactly because those are the (platform-specific) legacy IRQs.
> Currently the sfi spec doesn't mention anything explicitly. I > took a quick read through it and sfi and I presume Moorestown > is talking about non pci irqs. So I would not be surprised > if we didn't have isa device drivers running on platforms > without i8259s.
I'm confused about the above. Where do you see any mention to fixed (ISA) IRQs in SFI or Moorestown? Jacob tells me they don't exist.
> Currently the code had a small bug dealing with multiple ioapics and > the spec really is incomplete about how you map irqs from pci devices > to interrupts. So it looks like SFI and Moorestown are more a lab > experiment than real hardware at the moment. So I expect when > it gets completely fleshed out we will have to jump through a > similar set of hoops as we do with acpi to ensure the first 16 > irqs are not used for anything except isa irqs.
Moorestown hardware certainly exists, although not all the support is upstream yet.
Either which way, anything which perpetuates NR_IRQS_LEGACY as a compile-time constant is begging for people to get things wrong, and it really needs to go away.
-hpa
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