How to verify RX checksum offload??
How to verify RX checksum offload??
- Subject: How to verify RX checksum offload??
- From: Chfon <email@hidden>
- Date: Tue, 7 Jul 2009 11:15:20 +0800 (CST)
When checksum offload is enabled, the driver calls setChecksumResult method to encode the checksum result on the each received packet before passing it up towards the protocol stacks.
I want to verify checksum value computed by the hardware on received packets is correct or not. It is really not easy for me. It is because if the hardware provides error checksum value, protocol stacks seems re-calculate no matter in full or
partial checksum mode.
For instance, in partial checksum mode, driver provides a partial 16-bit checksum value to allow the protocol stacks to calculate and verify the final checksum. But if the driver provides error partial checksum value, the protocol stacks seems re-calculate checksum value and without any signal or log to tell users, even tcpstat.tcps_rcvbadsum's value has not increased. So I could not know the checksum value that hardware provided is correct or not.
Question:
1. Does the OSX shows any message or log to User while stacks indicates a bad checksum calculated by h/w?
2. In a received packet, from which byte to which byte is the partial
checksum calculated?
3. Does the calculation of partial checksum include the trailer?
4. If CRC code is appended into each packet, does partial checksum have to be calculated the CRC code?
5. Does the driver need to provide partial checksum to all the protocols?
Any reply would appreciated...
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