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NAME
iflibtxrx — Device Dependent Transmit and Receive Functions
SYNOPSIS
#include <ifdi_if.h>
Interface Manipulation Functions
int
isc_txd_encap(void *sc, if_pkt_into_t pi);
void
isc_txd_flush(void *sc, uint16_t qid, uint32_t _pidx_or_credits_);
int
isc_txd_credits_update(void *sc, uint16_t qid, bool clear);
int
isc_rxd_available(void *sc, uint16_t qsid, uint32_t cidx);
void
isc_rxd_refill(void *sc, uint16_t qsid, uint8_t flid, uint32_t pidx, uint64_t *paddrs,
caddr_t *vaddrs, uint16_t count);
void
isc_rxd_flush(void *sc, uint16_t qsid, uint8_t flid, uint32_t pidx);
int
isc_rxd_pkt_get(void *sc, if_rxd_info_t ri);
Global Variables
extern struct if_txrx
DATA STRUCTURES
The device dependent mechanisms for handling packet transmit and receive are primarily
defined by the functions named above. The if_pkt_info data structure contains statistics
and identifying info necessary for packet transmission. While the data structure for packet
receipt is the if_rxd_info structure.
The if_pkt_info Structure
The fields of struct if_pkt_info are as follows:
ipi_len (uint32_t) Denotes the size of packet to be sent on the transmit
queue.
ipi_segs (bus_dma_segment_t *) A pointer to the bus_dma_segment of the device
independent transfer queue defined in iflib.
ipi_qsidx Unique index value assigned sequentially to each transmit queue.
Used to reference the currently transmitting queue.
ipi_nsegs (uint16_t) Number of descriptors to be read into the device dependent
transfer descriptors.
ipi_ndescs (uint16_t) Number of descriptors in use. Calculated by subtracting
the old pidx value from the new pidx value.
ipi_flags (uint16_t) Flags defined on a per packet basis.
ipi_pidx (uint32_t) Value of first pidx sent to the isc_encap function for
encapsulation and subsequent transmission.
ipi_new_pidx (uint32_t) Value set after the termination of the isc_encap function.
This value will become the first pidx sent to the isc-encap the next
time that the function is called.
The Following Fields Are Used For Offload Handling
ipi_csum_flags (uint64_t) Flags describing the checksum values, used on a per packet
basis.
ipi_tso_segsz (uint16_t) Size of the TSO Segment Size.
ipi_mflags (uint16_t) Flags describing the operational parameters of the mbuf.
ipi_vtag (uint16_t) Contains the VLAN information in the Ethernet Frame.
ipi_etype (uint16_t) Type of ethernet header protocol as contained by the
struct ether_vlan_header.
ipi_ehrdlen (uint8_t) Length of the Ethernet Header.
ipi_ip_hlen (uint8_t) Length of the TCP Header
ipi_tcp_hlen (uint8_t) Length of the TCP Header.
ipi_tcp_hflags (uint8_t) Flags describing the operational parameters of the TCP
Header.
ipi_ipproto (uint8_t) Specifies the type of IP Protocol in use. Example TCP,
UDP, or SCTP.
The if_rxd_info Structure
The fields of struct if_rxd_info are as follows:
iri_qsidx (uint16_t) Unique index value assigned sequentially to each receive
queue. Used to reference the currently receiving queue.
iri_vtag (uint16_t) Contains the VLAN information in the Ethernet Frame.
iri_len (uint16_t) Denotes the size of a received packet.
iri_next_offset (uint16_t) Denotes the offset value for the next packet to be
receive. A Null value signifies the end of packet.
iri_cidx (uint32_t) Denotes the index value of the packet currently being
processed in the consumer queue.
iri_flowid (uint32_t) Value of the RSS hash for the packet.
iri_flags (uint)
Flags describing the operational parameters of the mbuf contained in
the
receive packet.
iri_csum_flags (uint32_t) Flags describing the checksum value contained in the
receive packet.
iri_csum_data (uint32_t) Checksum data contained in the mbuf(9) packet header.
iri_m (struct mbuf *) A mbuf for drivers that manage their own receive
queues.
iri_ifp (struct ifnet *) A link back to the interface structure. Utilized by
drivers that have multiple interface per softc.
iri_rsstype (uint8_t) The value of the RSS hash type.
iri_pad (uint8_t) The length of any padding contained by the received data.
iri_qidx (uint8_t) Represents the type of queue event. If value >= 0 then it
is the freelist id otherwise it is a completion queue event.
FUNCTIONS
All function calls are associated exclusively with either packet transmission or receipt.
The void *sc passed as the first argument to all of the following functions represents the
driver's softc.
Transmit Packet Functions
isc_txd_encap()
Transmit function that sends a packet on an interface. The if_pkt_info data structure
contains data information fields describing the packet. This function returns 0 if
successful, otherwise an error value is returned.
isc_txd_flush()
Flush function is called immediately after the isc_txd_encap function transmits a
packet. It updates the hardware producer index or increments the descriptors used to
pidx_or_credits in the queue designated by the qid number. This is often referred to
as poking the doorbell register.
isc_txd_credits_update()
Credit function advances the buffer ring and calculates the credits (descriptors)
processed. Until the I/O is complete it cleans the range in case of multisegments and
updates the count of processed packets. The function returns the number of processed
credits.
Receive Packet Functions
isc_rxd_available()
Function calculates the remaining number of descriptors from a position given by idx.
The function returns this value.
isc_rxd_refill()
Starting with the physical address paddrs, the function reads a packet into the
rx_ring until a value designated by count is reached. vaddrs is typically not needed
and is provided for devices that place their own metadata in the packet header.
isc_rxd_flush()
Flush function updates the producer pointer on the free list flid in queue set number
qid to pidx to reflect the presence of new buffers.
isc_rxd_pkt_get()
Process a single software descriptor. rxr->rx_base[i] contains a descriptor that
describes a received packet. Hardware specific information about the buffer referred
to by ri is returned in the data structure if_rxd_info
SEE ALSO
iflibdd(9), iflibdi(9), mbuf(9)
AUTHORS
This manual page was written by Nicole Graziano