Description
Prepare to send up to size bytes. Allocate TCP headers and prepare them with Ethernet IP/TCP header data - including current sequence number and acknowledgment number.
Definition
enum onload_delegated_send_prepare (
int fd,
int size,
uint flags,
struct onload_delegated_send* )Formal Parameters
-
fd - File descriptor to send on.
-
size - Size of payload data.
-
flags - See below.
-
struct onload_delegated_send* - See struct onload_delegated_send.
Return Value
Refer to onload_delegated_send_rc above.
Notes
This function can be called speculatively so that the packet buffer is prepared in advance, headers are added so that the packet payload data can be added immediately before the send is required.
This function assumes the packet length is equal to MSS in which case there is no need to call onload_delegated_send_tcp_update().
Flags are used for ARP resolution:
- default flags = 0
-
ONLOAD_DELEGATED_SEND_FLAG_IGNORE_ARP- do not do ARP lookup, the caller will provide destination MAC address. -
ONLOAD_DELEGATED_SEND_FLAG_RESOLVE_ARP- if ARP information is not available, send a speculative TCP_ACK to provoke kernel into ARP resolution, and wait up to 1 ms for ARP information to appear.
Note:
TCP send window/congestion windows must be respected during delegated
sends.
See extensions.h for flags and return code values.