recvmsg on AF_XDP

recvmsg on AF_XDP

[Ben LaGreca]

Is it possible to use recvmsg/read on an AF_XDP socket? I've been able
to set up a socket, write an XDP program, and properly receive frames
in UMEM with the RX and Fill rings, but am more interested in using
standard linux C functions. Some libxdp documentation mentions the use
of poll and sendto/recvmsg, and I have successfully polled the socket
(as one would a normal AF_INET socket), but can't find documentation
on clearing the revents status after a poll. Any help or redirection
to documentation would be appreciated.

-- Ben LaGreca

Re: recvmsg on AF_XDP

[Maciej Fijalkowski]

On Tue, Jul 23, 2024 at 07:28:12PM -0400, Ben LaGreca wrote:
> Is it possible to use recvmsg/read on an AF_XDP socket? I've been able
> to set up a socket, write an XDP program, and properly receive frames
> in UMEM with the RX and Fill rings, but am more interested in using
> standard linux C functions. Some libxdp documentation mentions the use
> of poll and sendto/recvmsg, and I have successfully polled the socket
> (as one would a normal AF_INET socket), but can't find documentation
> on clearing the revents status after a poll. Any help or redirection
> to documentation would be appreciated.

Are you aware of
https://github.com/xdp-project/bpf-examples/tree/master/AF_XDP-example

?

> 
> -- Ben LaGreca
> 

Re: recvmsg on AF_XDP

[Magnus Karlsson]

On Wed, 24 Jul 2024 at 01:37, Ben LaGreca <benlagreca02@gmail.com> wrote:
>
> Is it possible to use recvmsg/read on an AF_XDP socket? I've been able
> to set up a socket, write an XDP program, and properly receive frames
> in UMEM with the RX and Fill rings, but am more interested in using
> standard linux C functions. Some libxdp documentation mentions the use
> of poll and sendto/recvmsg, and I have successfully polled the socket
> (as one would a normal AF_INET socket), but can't find documentation
> on clearing the revents status after a poll. Any help or redirection
> to documentation would be appreciated.

sendto() and recvmsg() are only used to "wake up" the driver when you
are using an AF_XDP socket. poll() can be used for this too and also
to wait for an Rx or Tx event. But most of the standard Linux C
functions cannot be used with an AF_XDP socket. You have to use the
rings and the umem. Less convenient, but faster.

> -- Ben LaGreca
>