---
name: "rdma_post_send"
section: "3"
platform: "linux"
package: "rdma-core"
version: "65.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/rdma_post_send"
---

# rdma\_post\_send(3)

post a work request to send a message.

## NAME

rdma\_post\_send - post a work request to send a message.

## SYNOPSIS

**#include \<rdma/rdma\_verbs.h\>**

**int rdma\_post\_send** **(struct rdma\_cm\_id \****id***,** **void \****context***,** **void \****addr***,** **size\_t** *length***,** **struct ibv\_mr \****mr***,** **int** *flags***);**

## ARGUMENTS

- id

  A reference to a communication identifier where the message buffer will be posted.

- context

  User-defined context associated with the request.

- addr

  The address of the memory buffer to post.

- length

  The length of the memory buffer.

- mr

  Optional registered memory region associated with the posted buffer.

- flags

  Optional flags used to control the send operation.

## DESCRIPTION

Posts a work request to the send queue of the queue pair associated with the rdma\_cm\_id.  The contents of the posted buffer will be sent to the remote peer of a connection.

## RETURN VALUE

Returns 0 on success, or -1 on error.  If an error occurs, errno will be set to indicate the failure reason.

## NOTES

The user is responsible for ensuring that the remote peer has queued a receive request before issuing the send operations.  For a list of supported flags, see ibv\_post\_send.  Unless the send request is using inline data, the message buffer must have been registered before being posted, with the mr parameter referencing the registration. The buffer must remain registered until the send completes.

Send operations may not be posted to an rdma\_cm\_id or the corresponding queue pair until it has been connected.

The user-defined context associated with the send request will be returned to the user through the work completion wr\_id, work request identifier, field.

## SEE ALSO

[rdma\_cm(7)](/rdma_cm/7.md), [rdma\_connect(3)](/rdma_connect/3.md), [rdma\_accept(3)](/rdma_accept/3.md), [ibv\_post\_send(3)](/ibv_post_send/3.md), [rdma\_post\_sendv(3)](/rdma_post_sendv/3.md), [rdma\_post\_recv(3)](/rdma_post_recv/3.md)