Change Details

Add capabilities `TXCSUM` and `TXCSUM6` for TCP and UDP to the epair interface. It allows to enable these capabilities. They are disabled by default (it is planned to enable them by default at a later point in time). Both capabilities are synchronized between the two epair interface ends. If enabled/disabled on one end, it will be enabled/disabled on the other end. With `TXCSUM` or `TXCSUM6` enabled, the sender does not compute the checksum but sets the mbuf flag `CSUM_TCP` or `CSUM_UDP`. The sending epair interface end just transmits the mbuf with the flag set to the other epair interface end. If the packet in the mbuf leaves the host, because, after received by the other end, a bridge switches or IP routes the packet out over a physical interface, that interface computes the checksum. If the sending epair interface end has `TXCSUM` or `TXCSUM6` enabled and the receiving end is in a bridge, it is assumed that all interfaces in the bridge have that capability enabled. Otherwise the bridge would have disabled that capability on the receiving epair interface end in the bridge which would have disabled that capability on the sending epair interface end as well due to the synchronization. Note that in case the packet leaves the host due to IP routing, the outgoing interface may not have `TXCSUM` or `TXCSUM6` enabled. The code changes in D51475 compute the checksum in software in that case. Also note that if the packet is for the local host, the code changes in D51475 let the host accept the packet even if the checksum is incorrect due to offloading.

Add capabilities `RXCSUM` and `RXCSUM6` as well as `TXCSUM` and `TXCSUM6` for TCP and UDP to the epair interface and enable them by default. `RXCSUM` and `RXCSUM6` are enabled because an epair interface may receive a packet with the mbuf flag `CSUM_DATA_VALID` set, which is expected only if these capabilities are enabled. Since it seems not helpful to remove this flag, it is not possible to disable these capabilities. With `TXCSUM` or `TXCSUM6` enabled, the sender does not compute the checksum but sets the mbuf flag `CSUM_TCP` or `CSUM_UDP`. The sending epair interface end just transmits the mbuf with the flag set to the other epair interface end. If the packet in the mbuf leaves the host, because, after received by the other end, a bridge switches or IP routes the packet out over a physical interface, that interface computes the checksum. `TXCSUM` and `TXCSUM6` are synchronized between the two epair interface ends. If enabled/disabled on one end, it will be enabled/disabled on the other end. If the sending epair interface end has `TXCSUM` or `TXCSUM6` enabled and the receiving end is in a bridge, it is assumed that all interfaces in the bridge have that capability enabled. Otherwise the bridge would have disabled that capability on the receiving epair interface end in the bridge which would have disabled that capability on the sending epair interface end as well due to the synchronization. Note that in case the packet leaves the host due to IP routing, the outgoing interface may not have `TXCSUM` or `TXCSUM6` enabled. Since the code changes in D51475 the checksum is computed in software in that case. Also note that if the packet is for the local host, since the code changes in D51475 the host accept the packet even if the checksum is incorrect due to offloading.

Add capabilities `RXCSUM` and `RXCSUM6` as well as `TXCSUM` and `TXCSUM6` for TCP and UDP to the epair interface. It allows to enable these capabilities. They are disabled by default (it is planned to enable them by default at a later point in time). Both capabilities are synchronized between the two epair interface ends. If enabled/disabled on one end, it will be enabled/disabled on the other end and enable them by default. `RXCSUM` and `RXCSUM6` are enabled because an epair interface may receive a packet with the mbuf flag `CSUM_DATA_VALID` set, which is expected only if these capabilities are enabled. Since it seems not helpful to remove this flag, it is not possible to disable these capabilities. With `TXCSUM` or `TXCSUM6` enabled, the sender does not compute the checksum but sets the mbuf flag `CSUM_TCP` or `CSUM_UDP`. The sending epair interface end just transmits the mbuf with the flag set to the other epair interface end. If the packet in the mbuf leaves the host, because, after received by the other end, a bridge switches or IP routes the packet out over a physical interface, that interface computes the checksum. `TXCSUM` and `TXCSUM6` are synchronized between the two epair interface ends. If enabled/disabled on one end, it will be enabled/disabled on the other end. If the sending epair interface end has `TXCSUM` or `TXCSUM6` enabled and the receiving end is in a bridge, it is assumed that all interfaces in the bridge have that capability enabled. Otherwise the bridge would have disabled that capability on the receiving epair interface end in the bridge which would have disabled that capability on the sending epair interface end as well due to the synchronization. Note that in case the packet leaves the host due to IP routing, the outgoing interface may not have `TXCSUM` or `TXCSUM6` enabled. TheSince the code changes in D51475 compute the checksumthe checksum is computed in software in that case. Also note that if the packet is for the local host, since the code changes in D51475 let the host accept the packet even if the checksum is incorrect due to offloading.