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x86: add _PAGE_IOMAP pte flag for IO mappings

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Use one of the software-defined PTE bits to indicate that a mapping is
intended for an IO address.  On native hardware this is irrelevent,
since a physical address is a physical address.  But in a virtual
environment, physical addresses are also virtualized, so there needs
to be some way to distinguish between pseudo-physical addresses and
actual hardware addresses; _PAGE_IOMAP indicates this intent.

By default, __supported_pte_mask masks out _PAGE_IOMAP, so it doesn't
even appear in the final pagetable.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge
2008-09-07 15:21:13 -07:00
committed by Ingo Molnar
parent 07bb2f6236
commit be43d72835
4 changed files with 18 additions and 8 deletions
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8
arch/x86/mm/ioremap.c
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@@ -242,16 +242,16 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
switch (prot_val) {
case _PAGE_CACHE_UC:
default:
prot = PAGE_KERNEL_NOCACHE;
prot = PAGE_KERNEL_IO_NOCACHE;
break;
case _PAGE_CACHE_UC_MINUS:
prot = PAGE_KERNEL_UC_MINUS;
prot = PAGE_KERNEL_IO_UC_MINUS;
break;
case _PAGE_CACHE_WC:
prot = PAGE_KERNEL_WC;
prot = PAGE_KERNEL_IO_WC;
break;
case _PAGE_CACHE_WB:
prot = PAGE_KERNEL;
prot = PAGE_KERNEL_IO;
break;
}