VLAN support

[lhoward]

It would be useful to set a VLAN tag to apply to all inbound and outbound IP packets (i.e. use a trunk port). For our application a single global VLAN tag would suffice, we just need to distinguish from non-IP packets with different VIDs.

[humphrey-xmos]

Some note on supporting VLAN for lib_xtcp and possible changes,

• lib_ethernet config: enable_strip_vlan_tag()/disable_strip_vlan_tag() as needed
• lib_xtcp: check/set buffer sizes, extend minimum size 60 -> 64, check MTU sizes used.
• lib_xtcp config changes:
  • enable ETHARP_SUPPORT_VLAN (lwipopts.h)
  • Check which of following is needed,
    • LWIP_HOOK_VLAN_CHECK / ETHARP_VLAN_CHECK / ETHARP_VLAN_CHECK_FN
    • LWIP_HOOK_VLAN_SET / LWIP_VLAN_PCP
• lib_xtcp API changes:
  • add get/set functions for VLAN filtering/applying, or other way to use tags?

[lhoward]

enable_strip_vlan_tag() isn't supported on the GEMAC FYI.