dat_lmr_create

- register a memory region with an IA

Synopsis

cc [ flag… ] file… -ldat [ library… ] 
#include <dat/udat.h>

DAT_RETURN
    dat_lmr_create (
    IN    DAT_IA_HANDLE          ia_handle,
    IN    DAT_MEM_TYPE           mem_type,
    IN    DAT_REGION_DESCRIPTION region_description,
    IN    DAT_VLEN               length,
    IN    DAT_PZ_HANDLE          pz_handle,
    IN    DAT_MEM_PRIV_FLAGS     mem_privileges,
    OUT   DAT_LMR_HANDLE         *lmr_handle,
    OUT   DAT_LMR_CONTEXT        *lmr_context,
    OUT   DAT_RMR_CONTEXT        *rmr_context,
    OUT   DAT_VLEN               *registered_size,
    OUT   DAT_VADDR              *registered_address
    )

Parameters

ia_handle

Handle for an open instance of the IA.

mem_type

Type of memory to be registered. The following list outlines the memory type specifications.

DAT_MEM_TYPE_VIRTUAL

Consumer virtual memory.

Region description: A pointer to a contiguous user virtual range.

Length: Length of the Memory Region.

DAT_MEM_TYPE_SO_VIRTUAL

Consumer virtual memory with strong memory ordering. This type is a Solaris specific addition. If the ia_handle was opened without RO_AWARE_ (see dat_ia_open(3DAT)), then type DAT_MEM_TYPE_VIRTUAL is implicitly converted to this type.

Region description: A pointer to a contiguous user virtual range.

Length: Length of the Memory Region.

DAT_MEM_TYPE_LMR

LMR.

Region description: An LMR_handle.

Length: Length parameter is ignored.

DAT_MEM_TYPE_SHARED_VIRTUAL

Shared memory region. All DAT Consumers of the same uDAPL Provider specify the same Consumer cookie to indicate who is sharing the shared memory region. This supports a peer-to-peer model of shared memory. All DAT Consumers of the shared memory must allocate the memory region as shared memory using Platform-specific primitives.

Region description: A structure with 2 elements, where the first one is of type DAT_LMR_COOKIE and is a unique identifier of the shared memory region, and the second one is a pointer to a contiguous user virtual range.

Length: Length of the Memory Region

region_description

Pointer to type-specific data describing the memory in the region to be registered. The type is derived from the mem_type parameter.

length

Length parameter accompanying the region_description.

pz_handle

Handle for an instance of the Protection Zone.

mem_privileges:

Consumer-requested memory access privileges for the registered local memory region. The Default value is DAT_MEM_PRIV_NONE_FLAG. The constant value DAT_MEM_PRIV_ALL_FLAG = 0x33, which specifies both Read and Write privileges, is also defined. Memory privilege definitions are as follows:

Local Read

DAT_MEM_PRIV_LOCAL_READ_FLAG

0x01

Local read access requested.

Local Write

DAT_MEM_PRIV_LOCAL_WRITE_FLAG

0x10

Local write access requested.

Remote Read

DAT_MEM_PRIV_REMOTE_READ_FLAG

0x02

Remote read access requested.

Remote Write

DAT_MEM_PRIV_REMOTE_WRITE_FLAG

0x20

Remote write access requested.

lmr_handle

Handle for the created instance of the LMR.

lmr_context

Context for the created instance of the LMR to use for DTO local buffers.

registered_size

Actual memory size registered by the Provider.

registered_address

Actual base address of the memory registered by the Provider.

Description

The dat_lmr_create() function registers a memory region with an IA. The specified buffer must have been previously allocated and pinned by the uDAPL Consumer on the platform. The Provider must do memory pinning if needed, which includes whatever OS-dependent steps are required to ensure that the memory is available on demand for the Interface Adapter. uDAPL does not require that the memory never be swapped out; just that neither the hardware nor the Consumer ever has to deal with it not being there. The created lmr_context can be used for local buffers of DTOs and for binding RMRs, and lmr_handle can be used for creating other LMRs. For uDAPL the scope of the lmr_context is the address space of the DAT Consumer.

The return values of registered_size and registered_address indicate to the Consumer how much the contiguous region of Consumer virtual memory was registered by the Provider and where the region starts in the Consumer virtual address.

The mem_type parameter indicates to the Provider the kind of memory to be registered, and can take on any of the values defined in the table in the PARAMETERS section.

The pz_handle parameter allows Consumers to restrict local accesses to the registered LMR by DTOs.

DAT_LMR_COOKIE is a pointer to a unique identifier of the shared memory region of the DAT_MEM_TYPE_SHARED_VIRTUAL DAT memory type. The identifier is an array of 40 bytes allocated by the Consumer. The Provider must check the entire 40 bytes and shall not interpret it as a null-terminated string.

The return value of rmr_context can be transferred by the local Consumer to a Consumer on a remote host to be used for an RDMA DTO.

If mem_privileges does not specify remote Read and Write privileges, rmr_context is not generated and NULL is returned. No remote privileges are given for Memory Region unless explicitly asked for by the Consumer.

Return Values

DAT_SUCCESS

The operation was successful.

DAT_UNSUFFICIENT_RESOURCES

The operation failed due to resource limitations.

DAT_INVALID_PARAMETER

Invalid parameter.

DAT_INVALID_HANDLE

Invalid DAT handle.

DAT_INVALID_STATE

Parameter in an invalid state. For example, shared virtual buffer was not created shared by the platform.

DAT_MODEL_NOT_SUPPORTED

The requested Model was not supported by the Provider. For example, requested Memory Type was not supported by the Provider.

Usage

Consumers can create an LMR over the existing LMR memory with different Protection Zones and privileges using previously created IA translation table entries.

The Consumer should use rmr_context with caution. Once advertised to a remote peer, the rmr_context of the LMR cannot be invalidated. The only way to invalidate it is to destroy the LMR with dat_lmr_free(3DAT).

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

dat_lmr_free(3DAT), libdat(3LIB), attributes(5)