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iflibtxrx — Device Dependent Transmit and Receive Functions
Contents
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.
Theif_pkt_infoStructure
The fields of structif_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.
TheFollowingFieldsAreUsedForOffloadHandlingipi_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.
Theif_rxd_infoStructure
The fields of structif_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 (structmbuf*) A mbuf for drivers that manage their own receive queues.
iri_ifp (structifnet*) 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.
TransmitPacketFunctionsisc_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.
ReceivePacketFunctionsisc_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
Name
iflibtxrx — Device Dependent Transmit and Receive Functions
See Also
iflibdd(9), iflibdi(9), mbuf(9)
Synopsis
#include<ifdi_if.h>InterfaceManipulationFunctionsintisc_txd_encap(void*sc, if_pkt_into_tpi);
voidisc_txd_flush(void*sc, uint16_tqid, uint32_t_pidx_or_credits_);
intisc_txd_credits_update(void*sc, uint16_tqid, boolclear);
intisc_rxd_available(void*sc, uint16_tqsid, uint32_tcidx);
voidisc_rxd_refill(void*sc, uint16_tqsid, uint8_tflid, uint32_tpidx, uint64_t*paddrs, caddr_t*vaddrs,
uint16_tcount);
voidisc_rxd_flush(void*sc, uint16_tqsid, uint8_tflid, uint32_tpidx);
intisc_rxd_pkt_get(void*sc, if_rxd_info_tri);
GlobalVariablesexternstructif_txrx
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