Add a parameter to specify the socket priority to txrx-tsn

[xtor]

The vlan-prio command line option is used to specify the PCP value and the socket priority:

	{"vlan-prio",	'q',	"NUM",	0, "packet vlan priority, also socket priority\n"
					   "	Def: 0 | Min: 0 | Max: 7"},

The value supplied, between 0 and 7, is then used to:

• Set the socket prio
• Set the XDP queue to be used
• Set the PCP value

	case 'q':
		len = strlen(arg);
		res = strtol((const char *)arg, &str_end, 10);
		if (errno || res < 0 || res >= 7 || str_end != &arg[len])
			exit_with_error("Invalid queue number/socket priority. Check --help");
		opt->socket_prio = (uint32_t)res;
#ifdef WITH_XDP
		opt->x_opt.queue = opt->socket_prio;
#endif
		opt->vlan_prio = opt->socket_prio * 32;
		break;

Implementation suggestion

The implementation would require to parse a new option for 'socket-prio'. The behavior would be as follows:

• AF_PACKET (socket mode afpkt parameter)

  • Only vlan-prio is provided: same behavior as of now, to keep backwards compatibility.
  • Only socket-prio is provided
    • Check that the value is in the 0 to 15 range
    • Initialize opt->socket_prio to the value provided for the parameter
    • Leave opt->vlan_prio with the default value
  • Both are provided: vlan-prio is configured first as when only vlan-prio is provided. Then, on top of it, apply the socket-prio configuration as above: check that the value is in the 0-15 range, and then initialize opt->socket_prio to the value provided for the parameter. opt->vlan_prio remains with the value provided for the vlan-prio parameter.

• AF_XDP (socket mode afxdp parameter)

  • Only vlan-prio is provided: same behavior as of now, to keep backwards compatibility.
  • Only socket-prio is provided: raise an error and inform that AF_XDP sockets do not implement a socket priority
  • Both are provided: raise an error and inform that AF_XDP sockets do not implement a socket priority

@AzuraTarmiziIntel could you please provide some guidance about how to proceed with this usage of socket_prio?

• iotg_tsn_ref_sw/src/txrx-afpkt.c

  Line 220 in 0ee32cd

  memcpy(&payload->tx_queue, &opt->socket_prio, sizeof(uint32_t));

• iotg_tsn_ref_sw/src/txrx-afpkt.c

  Line 353 in 0ee32cd

  memcpy(&payload->tx_queue, &opt->socket_prio, sizeof(uint32_t));