Messages in this thread |  | | Date | Thu, 9 Jan 2003 17:09:06 -0800 | Subject | Re: [patch 2.5] 2-pass PCI probing, generic part | From | (Grant Grundler) |
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On Thu, Jan 09, 2003 at 03:35:32PM -0800, Linus Torvalds wrote: > The only real reason to worry about BAR sizing is really to do resource > discovery in order to make sure that out bridges have sufficiently big > windows for the IO regions. Agreed?
yes. And eventually to make sure regions don't overlap.
> And that should be a non-issue especially on a host bridge, since we > almost certainly don't want to reprogram the bridge windows there anyway.
Current PARISC servers do not allocate MMIO/IO resources for all PCI devices. Only boot devices are configured. Fortunately, default MMIO/IO address space assigned to Host bridges seems to work - at least I've not heard anyone complain (yet). But no one has tried PCI expansion chassis or cards with massive (> 64MB) MMIO BARs.
Because of PCI hotplug, rumor is ia64 firmware folks want to do the same thing in the near future.
> So I'd like to make the _default_ be to probe the minimal possible, > _especially_ for host bridges. Then, the PCI quirks could be used to > expand on that default.
That's reasonable. pci arch code also has hooks to fixup host bridge resources.
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