This makes the user interface a little hostile. People thing of an MTU of 1500 bytes, but the corresponding packet is really 1514 bytes (including the 14 byte Ethernet header). A more friendly solution would configure the MTU (as before), but then derive the packet buffer size by adding the MAC header length. Instead, we define the packet buffer size then derive the MTU.
The MTU is not common currency in networking. On the wire, the only real issue is the MSS which is derived from MTU by subtracting the IP header and TCP header sizes (for the case of TCP). Now it is derived for the PKTSIZE by subtracting the IP header, the TCP header, and the MAC header sizes. So we should be all good and without the recurring 14 byte error in MTU's and MSS's.
Squashed commit of the following:
Trivial update to fix some spacing issues.
net/: Rename several macros containing _MTU to _PKTSIZE.
net/: Rename CONFIG_NET_SLIP_MTU to CONFIG_NET_SLIP_PKTSIZE and similarly for CONFIG_NET_TUN_MTU. These are not the MTU which does not include the size of the link layer header. These are the full size of the packet buffer memory (minus any GUARD bytes).
net/: Rename CONFIG_NET_6LOWPAN_MTU to CONFIG_NET_6LOWPAN_PKTSIZE and similarly for CONFIG_NET_TUN_MTU. These are not the MTU which does not include the size of the link layer header. These are the full size of the packet buffer memory (minus any GUARD bytes).
net/: Rename CONFIG_NET_ETH_MTU to CONFIG_NET_ETH_PKTSIZE. This is not the MTU which does not include the size of the link layer header. This is the full size of the packet buffer memory (minus any GUARD bytes).
net/: Rename the file d_mtu in the network driver structure to d_pktsize. That value saved there is not the MTU. The packetsize is the memory large enough to hold the maximum packet PLUS the size of the link layer header. The MTU does not include the link layer header.
RNDIS support on STM32F4Discovery
* stm32f4discovery: Add stm32_netinit.c to avoid a compilation error
* stm32f4discovery: Add rndis initialization in stm32_bringup.c
NOTE: MAC address for the host side starts 0xaa. This assignment
scheme should be fixed later.
* stm32f4discovery: Add rndis configuration
NOTE: STM32F4Discovery + DM-STF4BB
* drivers/usbdev/rndis.c: Fix some issues in rndis.c
Introduce rndis_transmit() and change rndis_rxdispatch() to avoid
packet corruption. Introduce max packet size for dual speed which
is mainly used for high speed mode. Fix adjusting MTU warning
on Linux host. Fix data corruption if a packet size excceds MTU.
NOTE: Max packet size is not configured dynamically. This should
be fixed in the future version.
* stm32f4discovery: Modify #ifdef condition for rndis in stm32_bringup()
* drivers/usbdev/rndis.c: Change HPWORK to ETHWORK
* drivers/usbdev/rndis.c: Merge the commit 07b98ccbb5
Previous commit b09365784a was based on old rndis.c thus resulted
in reverting the commit 07b98ccbb5. This change merges the commit.
NOTE: In the commit 07b98ccbb5, max packet size of bulkout was
assumed to be 64. In this commit, priv->epbulkout->maxpacket is
used instead.
Approved-by: Gregory Nutt <gnutt@nuttx.org>
