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    SubjectRE: [openib-general] Re: [PATCH] arch/xx/pci: remap_pfn_range -> io_remap_pfn_range
    Date
    From
    > >     Greg> Hm, you do realize that io_remap_pfn_range() is the same
    > > Greg> thing as remap_pfn_range() on i386, right?
    > >
    > > Greg> So, why would this patch change anything?
    > >
    > > It's not the same thing under Xen. I think this patch
    > fixes userspace
    > > access to PCI memory for XenLinux.
    >
    > But Xen is a separate arch, and hence, will get different pci
    > arch specific functions, right?
    >
    > In short, what is this patch trying to fix? What is the
    > problem anyone is seeing with the existing code?

    As I understand it, remap_pfn_range should be used for mapping pages
    that are backed by memory, and io_remap_pfn_range should be used for
    mapping MMIO regions.
    There's a distinciton between the two for architectures like Sparc and
    xen/x86.

    For example, drivers/char/mem.c uses io_remap_pfn_range for mmap'ing
    /dev/mem

    Ian
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