How does FreeBSD handle tcp checksum offloading

[Andrew Falanga]

Hi,

I'm curious as to how FreeBSD handles checksum offloading for TCP
packets.  Is this on by default?  It seems that it's only relevant for
specific drivers rather than something that's just assumed.  How can I
determine if this is supported for the hardware I'm running?  Is it
common for tcp checksum offloading to be in the fxp driver?  Can one
turn it off (though, it honestly sounds like no one would wish to do
so)?

Andy