| Date | Mon, 01 Oct 2012 20:43:04 -0400 | From | Jon Masters <> | Subject | Re: [PATCH 10/36] AArch64: MMU definitions |
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On 07/06/2012 05:05 PM, Catalin Marinas wrote:
> +/* > + * PAGE_OFFSET - the virtual address of the start of the kernel image. > + * VA_BITS - the maximum number of bits for virtual addresses. > + * TASK_SIZE - the maximum size of a user space task. > + * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area. > + * The module space lives between the addresses given by TASK_SIZE > + * and PAGE_OFFSET - it must be within 128MB of the kernel text. > + */ > +#define PAGE_OFFSET UL(0xffffffc000000000) > +#define MODULES_END (PAGE_OFFSET) > +#define MODULES_VADDR (MODULES_END - SZ_64M) > +#define VA_BITS (39) > +#define TASK_SIZE_64 (UL(1) << VA_BITS)
Pedantic nit pick. Shouldn't that "it must be within 128MB of the kernel text" be "within 128MB of the *end* of the kernel text"? The point being that on AArch64 unconditional branches are encoded as imm26+1 (27 bits) and so you're going with -64MB to ensure that you're within the range.
Jon.
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