This thread sort of petered out, but I don't think we changed
anything, and I think we still have a problem. If so, I'd like to
capture it in a bugzilla so we don't forget about it.
I think the problem is that a driver (pci-stub or any other driver)
can't use request_mem_region() on a device BAR if that BAR happens to
conflict with an E820 reserved area.
>From Maxim's case, we have this:
BIOS-e820: 00000000fa000000 - 00000000fc000000 (reserved)
pci_root PNP0A08:00: host bridge window [mem 0xf0000000-0xfebfffff]
pci 0000:00:1c.0: PCI bridge to [bus 05-05]
pci 0000:00:1c.0: bridge window [mem 0xf0000000-0xfbffffff 64bit pref]
pci 0000:05:00.0: reg 14: [mem 0xf0000000-0xf7ffffff 64bit pref]
pci 0000:05:00.0: reg 1c: [mem 0xf8000000-0xfbffffff 64bit pref]
pci-stub 0000:05:00.0: BAR 3: can't reserve [mem
0xf8000000-0xfbffffff 64bit pref]
and the iomem_resource tree looks like this:
f0000000-febfffff : PCI Bus 0000:00
f0000000-fbffffff : PCI Bus 0000:05
f0000000-f7ffffff : 0000:05:00.0
f8000000-fbffffff : 0000:05:00.0
fa000000-fbffffff : reserved
The fa000000-fbffffff reserved area (from E820) doesn't cause us to
move the 05:00.0 BAR at 0xf8000000, but it does prevent us from
requesting that region in a driver. I think this is a bug.
Maxim, if you agree that this is still a problem, would you mind
opening a report at http://bugzilla.kernel.org? You can put it under
Drivers/PCI and CC me if you like.
Thanks,
Bjorn
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