Re: ohci1394 problem (MMIO broken) (was 2.6.25-rc6-git6: Reported regressions from 2.6.24)

[Yinghai Lu]

On Tue, Mar 25, 2008 at 4:33 PM, Benjamin Herrenschmidt <benh@xxxxxxxxxx> wrote:
> On Sat, 2008-03-22 at 14:33 -0700, Linus Torvalds wrote:
>  >
>  > On Sat, 22 Mar 2008, Stefan Richter wrote:
>  > >
>  > > Can an MMIO region reside above 0x1'0000'0000 on x86-32? ... Apparently yes,
>  > > if CONFIG_RESOURCES_64BIT=y.
>  >
>  > Hmm. It would only work if PAE (HIGHMEM64G) is enabled too.
>  >
>  > And obviously the hardware has to have working 64-bit BAR's.
>
>  On other platforms however, you can have mmio above 32 bits without
>  support for 64 bits BARs: the entire PCI bus mmio region can be mapped
>  up there.
>
>  That happens for example with 4xx embedded PowerPC. We deal with it just
>  fine, provided that nothing tries to stick a resource value into an
>  unsigned long but uses resource_size_t instead. Unfortunately, it's a
>  common bug, I've fixing drivers regulary.
>
>  It also appears that the iomap code on various archs is buggy too,
>  including the generic lib/iomap.c, thus pci_iomap is broken for archs
>  that can have 64 bits resources and use the version in lib/.
>
>  The good news is that I have done a patch to fix it, which has been
>  in -mm for about a month: iomap-fix-64-bits-resources-on-32-bits.patch

does it support if size is 4G above, like 256G?

YH
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