ibv_alloc_dmah(3)

NAME
ibv_alloc_dmah - allocate a dma handle

int ibv_dealloc_dmah - deallocate a dma handle

SYNOPSIS

        #include <infiniband/verbs.h>
        struct ibv_dmah *ibv_alloc_dmah(struct ibv_context *context, struct ibv_dmah_init_attr *attr);
        int ibv_dealloc_dmah(struct ibv_dmah *dmah);

DESCRIPTION
ibv_alloc_dmah() allocates an ibv_dmah object that is associated with the given context and the input attr parameter.

The allocated handle can be later used for optimizing DMA and RDMA operations associated with a registered memory region.

Once the ibv_dmah usage has been ended ibv_dealloc_dmah() should be called.

This call will release resources that were earlier allocated using the ibv_alloc_dmah() API.

ARGUMENTS

  attr

        enum ibv_tph_mem_type {
            IBV_TPH_MEM_TYPE_VM, /* volatile memory */
            IBV_TPH_MEM_TYPE_PM, /* persistent memory */
        };
        enum ibv_dmah_init_attr_mask {
            IBV_DMAH_INIT_ATTR_MASK_CPU_ID = 1 << 0,
            IBV_DMAH_INIT_ATTR_MASK_PH = 1 << 1,
            IBV_DMAH_INIT_ATTR_MASK_TPH_MEM_TYPE = 1 << 2,
        };
        struct ibv_dmah_init_attr {
            uint32_t comp_mask; /* From ibv_dmah_init_attr_mask */
            uint32_t cpu_id;
            uint8_t ph;
            uint8_t tph_mem_type; /* From enum ibv_tph_mem_type */
        };

comp_mask
    Bitmask specifying what fields in the structure are valid.

cpu_id
    The cpu id that the dma handle refers to.

ph  Processing hints, used to aid in optimizing the handling of transactions over PCIe.

tph_mem_type
    The target memory type, one among enum ibv_tph_mem_type.

RETURN VALUE
ibv_alloc_dmah() returns a pointer to the allocated dma handle object, or NULL if the request fails.

ibv_dealloc_dmah() returns 0 upon success, otherwise the errno value.

SEE ALSO
ibv_reg_mr_ex(3)

AUTHOR
Yishai Hadas yishaih@nvidia.com