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umad_recv(3) — Linux manual page

UMAD_RECV(3)            OpenIB Programmer's ManualUMAD_RECV(3)

NAME        top

       umad_recv - receive umad

SYNOPSIS        top

#include <infiniband/umad.h>int umad_recv(intportid, void*umad, int*length, inttimeout_ms);

DESCRIPTION        top

umad_recv()waits up totimeout_ms milliseconds for an incoming       MAD message to be received from the port specified byportid.       A MAD "message" consists of a single MAD packetor a coalesced       multipacket RMPP transmission.  In the RMPP case the header of the       first RMPP packet is returned as the header of the buffer and the       buffer data contains the coalesced data section of each subsequent       RMPP MAD packet within the transmission.  Thus all the RMPP       headers except the first are not copied to user space from the       kernel.       The message is copied to theumad buffer if there is sufficient       room and the receivedlength is indicated.  If the buffer is not       large enough, the size of the umad buffer needed is returned inlength.  A negativetimeout_ms makes the function block until a       packet is received. Atimeout_ms parameter of zero indicates a non       blocking read.Notelength is a pointer to the length of thedataportion of the       umad buffer.  This means thatumad must point to a buffer at least       umad_size() +*length bytes long.Note alsothat*length must be >= 256 bytes.  This length allows       for at least a single MAD packet to be returned.

RETURN VALUE        top

umad_recv()on success return the agentid; on error, errno is set       and a negative value is returned as follows:        -EINVAL      invalid port handle or agentid or *length is less       than the minimum supported        -EIO         receive operation failed        -EWOULDBLOCK non blocking read can't be fulfilled        -ENOSPC      The provided buffer is not long enough for the       complete message.

SEE ALSO        top

umad_poll(3)

AUTHOR        top

       Hal Rosenstock <halr@voltaire.com>

COLOPHON        top

       This page is part of therdma-core (RDMA Core Userspace Libraries       and Daemons) project.  Information about the project can be found       at ⟨https://github.com/linux-rdma/rdma-core⟩.  If you have a bug       report for this manual page, send it to       linux-rdma@vger.kernel.org.  This page was obtained from the       project's upstream Git repository       ⟨https://github.com/linux-rdma/rdma-core.git⟩ on 2025-08-11.  (At       that time, the date of the most recent commit that was found in       the repository was 2025-08-04.)  If you discover any rendering       problems in this HTML version of the page, or you believe there is       a better or more up-to-date source for the page, or you have       corrections or improvements to the information in this COLOPHON       (which isnot part of the original manual page), send a mail to       man-pages@man7.orgOpenIB                         May 11, 2007UMAD_RECV(3)

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