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ibv_alloc_dmah(3) Libibverbs Programmer’s Manual 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 */
};
Bitmask specifying what fields in the structure are valid.
The cpu id that the dma handle refers to.
Processing hints, used to aid in optimizing the handling of transactions over PCIe.
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

2025-5-8 libibverbs