Module Name:	src
Committed By:	jonathan
Date:		Fri Aug 22 03:32:36 UTC 2003

Modified Files:
	src/sys/dev/pci: if_bge.c

Log Message:
Check in hooks to fix checksum offload on bge devices. Empirical
observation is that some 570x devices can get themselves into a state
where they miscompute off-loaded TCP or UDP checksums on packets so
small that Ethernet padding is required.  Further obsevation suggests
that the bge checksum-offload hardware is adding those padding bytes
into its TCP checksum computation. (Once a 5700 gets in this state,
even a warm boot won't fix it: it needs a hard powerdown.)

Work around the problem by padding such runts with zeros: even if the
checksum-offload adds in extra zeros, the resulting sum will be correct.

Also, dont trust the checksum-offload on received packets smaller than
the minimum ethernet frame, in case the Rx-side has a similar bug.

Finally, on packets where we do trust the outboard Rx-side TCP or UDP
checksum, the bge did not include the pseudo-header. Set the
M_CSUM_NO_PSEUDOHDR bit as well as M_CSUM_DATA, and rely on
udp_input() or tcp_input() adding in the sum via in_cksum_phdr().


To generate a diff of this commit:
cvs rdiff -r1.45 -r1.46 src/sys/dev/pci/if_bge.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.