On 07/07/2012 05:36 AM, Peter Maydell wrote: > On 6 July 2012 20:26, Dave Martin <dave.mar...@linaro.org> wrote: >> On Fri, Jul 06, 2012 at 07:07:35PM +0100, Peter Maydell wrote: >>> On 6 July 2012 00:27, Rob Herring <robherri...@gmail.com> wrote: >>>> I would just change arm_add_memory to use phys_addr_t for the size >>>> param. This ultimately calls memblock functions which use phys_addr_t >>>> for sizes. >>> >>> So I have a patch that does this which basically works. However >>> there is a bit I'm not sure about. arm_add_memory() does this: >>> bank->size = size & PAGE_MASK; >>> >>> in an attempt to clear the bottom bits of the size. However, >>> since PAGE_MASK is defined as: >>> #define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT) >>> #define PAGE_MASK (~(PAGE_SIZE-1)) >>> >>> PAGE_MASK is a 32 bit unsigned constant and so this & will >>> clear the top 32 bits of bank->size. >>> >>> I'm really not sure what the best way to fix this is; suggestions? >> >> Maybe something like >> >> ~(phys_addr_t)~PAGE_MASK >> >> or >> >> ~(phys_addr_t)(PAGE_SIZE - 1) >> >> would work. > > Mmm. It feels a bit unsatisfactory that an "obviously correct" > line of code like "size &= ~PAGE_MASK" could actually be subtly > wrong (seems like the kind of thing that could easily slip > through code review), so I was wondering if maybe redefining > PAGE_MASK so it didn't do the wrong thing on 64 bit types > would be better. (That's definitely way out of my depth though.) >
While there is a mixture of usage of PAGE_MASK in the kernel, I think correct usage is with virt addresses. For phys addresses, there is PHYS_MASK which is sized correctly for LPAE. You really should post this on the lakml list. Rob > -- PMM > _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
