linux-4.4.1/cma_init_reserved_mem()

参照元†

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説明†

パス: linux-4.4.1/mm/cma.c

FIXME: これは何？
- 説明

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引数†

phys_addr_t base
- linux-4.4.1/phys_addr_t
phys_addr_t size
unsigned int order_per_bit
struct cma **res_cma
- linux-4.4.1/cma

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返り値†

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参考†

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実装†

/**
 * cma_init_reserved_mem() - create custom contiguous area from reserved memory
 * @base: Base address of the reserved area
 * @size: Size of the reserved area (in bytes),
 * @order_per_bit: Order of pages represented by one bit on bitmap.
 * @res_cma: Pointer to store the created cma region.
 *
 * This function creates custom contiguous area from already reserved memory.
 */
int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
                                 unsigned int order_per_bit,
                                 struct cma **res_cma)
{
        struct cma *cma;
        phys_addr_t alignment;

        /* Sanity checks */
        if (cma_area_count == ARRAY_SIZE(cma_areas)) {
                pr_err("Not enough slots for CMA reserved regions!\n");
                return -ENOSPC;
        }

        if (!size || !memblock_is_region_reserved(base, size))
                return -EINVAL;

- linux-4.4.1/memblock_is_region_reserved()

        /* ensure minimal alignment required by mm core */
        alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);

        /* alignment should be aligned with order_per_bit */
        if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
                return -EINVAL;

- linux-4.4.1/IS_ALIGNED()
- linux-4.4.1/PAGE_SHIFT

        if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
                return -EINVAL;

        /*
         * Each reserved area must be initialised later, when more kernel
         * subsystems (like slab allocator) are available.
         */
        cma = &cma_areas[cma_area_count];
        cma->base_pfn = PFN_DOWN(base);
        cma->count = size >> PAGE_SHIFT;
        cma->order_per_bit = order_per_bit;
        *res_cma = cma;
        cma_area_count++;
        totalcma_pages += (size / PAGE_SIZE);