cacheable PCIe BAR

Here's some comments in an old PCI mmap driver routine I wrote. Perhaps this still applies in the latest kernels ...

    /* Flags to stop the processor treating PCI memory as
     * cacheable (see asm-ppc/pgtable.h)
     *
     * (thanks to Travis Sawyer from the ppc-embedded list)
     *
     * I could have used '#ifdef CONFIG_44x', but 40x uses
     * these flags too, as do other processors. So just check
     * whether the flag exists.
     *
     * TODO:
     * p425 Rubini; use pgprot_noncached()
     *
     * asm-ppc/pgtable.h defines it as setting these two flags
     *
     * So, that appears to be the 'portable' way to do it.
     *
     * drivers/char/mem.c uses pgprot_noncached()
     */# ifdef pgprot_noncached
    vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);# endif