Tribblix: manual page: mac_lso

MAC_LSO_GET(9F) Kernel Functions for Drivers MAC_LSO_GET(9F)

NAME

mac_lso_get - get LSO information on message blocks

SYNOPSIS

#include <sys/mac_provider.h>

void
mac_lso_get(mblk_t *mp, uint32_t *mss, uint32_t *flags);

INTERFACE LEVEL

illumos DDI specific

PARAMETERS

mp A pointer to a mblk(9S) structure that contains an
outgoing frame.

mss A pointer to a value that will be filled in with the
maximum segment size (MSS).

flags A pointer to a value that will be filled in with various
flags that indicate the behavior to perform.

DESCRIPTION

The mac_lso_get() function is used by device drivers that have
indicated that they support the MAC_CAPAB_LSO capability to determine
whether large send offload (also known as large segmentation offload or
LSO) is required for this frame or not. If so, the driver should take
the appropriate actions to program the hardware to perform LSO.

The mac_lso_get() function should only be called on the first mblk_t
that begins a given individual frame in a chain. In other words, it
only works on entries where it is the first of many possible entries
linked together by the b_cont member. The first mblk_t received from
any mac(9E) API or pointed to by a b_next pointer should be used.

A device driver should first look at the flags argument to determine
what to do. flags may be a bitwise inclusive OR of the following:

HW_LSO This flag indicates that hardware needs to perform segmentation
offload. The maximum segment size that the driver should use
is available through the mss argument.

CONTEXT