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Document SO_NO_OFFLOADS and SO_NO_DDP.

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Reviewed by:	bcr, np
MFC after:	1 week
Sponsored by:	Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D25043
This commit is contained in:
John Baldwin 2020-06-03 18:59:31 +00:00
parent 093a8f8daf
commit ae84ff9c47
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=361767
1 changed files with 15 additions and 2 deletions
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17
lib/libc/sys/getsockopt.2
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@ -28,7 +28,7 @@
.\" @(#)getsockopt.2 8.4 (Berkeley) 5/2/95 .\" @(#)getsockopt.2 8.4 (Berkeley) 5/2/95
.\" $FreeBSD$ .\" $FreeBSD$
.\" .\"
.Dd September 11, 2019 .Dd June 03, 2020
.Dt GETSOCKOPT 2 .Dt GETSOCKOPT 2
.Os .Os
.Sh NAME .Sh NAME
@ -191,6 +191,8 @@ The following options are recognized in
.It Dv SO_USER_COOKIE Ta "set the 'so_user_cookie' value for the socket (uint32_t, set only)" .It Dv SO_USER_COOKIE Ta "set the 'so_user_cookie' value for the socket (uint32_t, set only)"
.It Dv SO_TS_CLOCK Ta "set specific format of timestamp returned by SO_TIMESTAMP" .It Dv SO_TS_CLOCK Ta "set specific format of timestamp returned by SO_TIMESTAMP"
.It Dv SO_MAX_PACING_RATE Ta "set the maximum transmit rate in bytes per second for the socket" .It Dv SO_MAX_PACING_RATE Ta "set the maximum transmit rate in bytes per second for the socket"
.It Dv SO_NO_OFFLOAD Ta "disables protocol offloads"
.It Dv SO_NO_DDP Ta "disables direct data placement offload"
.El .El
.Pp .Pp
.Dv SO_DEBUG .Dv SO_DEBUG
@ -512,7 +514,6 @@ the error status.
It may be used to check for asynchronous errors on connected It may be used to check for asynchronous errors on connected
datagram sockets or for other asynchronous errors. datagram sockets or for other asynchronous errors.
.Pp .Pp
Finally,
.Dv SO_LABEL .Dv SO_LABEL
returns the MAC label of the socket. returns the MAC label of the socket.
.Dv SO_PEERLABEL .Dv SO_PEERLABEL
@ -521,6 +522,7 @@ Note that your kernel must be compiled with MAC support.
See See
.Xr mac 3 .Xr mac 3
for more information. for more information.
.Pp
.Dv SO_LISTENQLIMIT .Dv SO_LISTENQLIMIT
returns the maximal number of queued connections, as set by returns the maximal number of queued connections, as set by
.Xr listen 2 . .Xr listen 2 .
@ -532,6 +534,17 @@ returns the number of unaccepted incomplete connections.
.Dv SO_MAX_PACING_RATE .Dv SO_MAX_PACING_RATE
instruct the socket and underlying network adapter layers to limit the instruct the socket and underlying network adapter layers to limit the
transfer rate to the given unsigned 32-bit value in bytes per second. transfer rate to the given unsigned 32-bit value in bytes per second.
.Pp
.Dv SO_NO_OFFLOAD
disables support for protocol offloads.
At present, this prevents TCP sockets from using TCP offload engines.
.Dv SO_NO_DDP
disables support for a specific TCP offload known as direct data
placement (DDP).
DDP is an offload supported by Chelsio network adapters that permits
reassembled TCP data streams to be received via zero-copy in
user-supplied buffers using
.Xr aio_read 2 .
.Sh RETURN VALUES .Sh RETURN VALUES
.Rv -std .Rv -std
.Sh ERRORS .Sh ERRORS