Re: [PATCH 4/7] swiotlb: Allow arch override of address_needs_mapping
From: Jeremy Fitzhardinge
Date: Wed Apr 08 2009 - 18:37:26 EST
FUJITA Tomonori wrote:
Some architectures need non-trivial bus<->phys conversion routines, etc,
Only Xen needs such conversion for swiotlb.
Becky's patches of last week also added __weak annotations to
swiotlb_bus_to_virt, virt_to_bus and bus_to_phys; added the hwdev
parameter to swiotlb_bus_to_phys; and added a weak
swiotlb_arch_address_needs_mapping. I assume that was needed because
powerpc needs non-trivial implementations for those functions.
so either we can require it that all architectures wishing to use
swiotlb define these functions, or have weak default functions that can
be overridden by architectures where necessary.
Can you give an example? I don't think IA64, X86_64 or POWER (which
will use swiotlb) need any __weak functions. If you say other archs
could use swiotlb, please tell me how they need these __weak.
As I said, Becky's patches added hooks in many of the places we added
them for Xen. I assume that's because powerpc needs them; I have not
seen the arch/powerpc side of those changes.
J
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