Simple messages

For simple single-part messages, the OS provides functions that take a pointer directly to a buffer without the need for an IOV (input/output vector). In this case, the number of parts is replaced by the size of the message directly pointed to.

In the case of the message send primitive—which takes a send and a reply buffer—this introduces four variations:

Function Send message Reply message
MsgSend() Simple Simple
MsgSendsv() Simple IOV
MsgSendvs() IOV Simple
MsgSendv() IOV IOV

The other messaging primitives that take a direct message simply drop the trailing “v” in their names:

IOV Simple direct
MsgReceivev() MsgReceive()
MsgReceivePulsev() MsgReceivePulse()
MsgReplyv() MsgReply()
MsgReadv() MsgRead()
MsgWritev() MsgWrite()