Messages in this thread | | | Date | Sun, 16 Mar 2014 09:46:50 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH v7 2/2] ARM hibernation / suspend-to-disk |
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On Mon, Mar 10, 2014 at 11:32:17AM -0700, Sebastian Capella wrote: > I've moved to this second implementation. I don't think I understand > the ramifications enough to add the virt_to_pfn call for arm.
Let's look at the implementations...
#define __pa(x) __virt_to_phys((unsigned long)(x)) static inline phys_addr_t __virt_to_phys(unsigned long x) { return (phys_addr_t)x - PAGE_OFFSET + PHYS_OFFSET; }
So, __pa() returns a phys_addr_t (which may be either 32-bit or 64-bit).
#define virt_to_pfn(kaddr) (__pa(kaddr) >> PAGE_SHIFT)
And that will do an appropriate shift to convert the phys_addr_t to a PFN, which will be fine to assign to an unsigned long variable.
#define __phys_to_pfn(paddr) ((unsigned long)((paddr) >> PAGE_SHIFT))
This does the same thing, but has an explicit cast.
So, the only difference between the two suggestions is that additional cast, which has no effect here.
> I've changed one thing. __nosave_end is pointing at the first byte > not included in the nosave region. I subtracted one from it so that > we make sure we're referring to the last pfn, and left the pfn > comparison as you'd suggested.
Yes, that should be safer.
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