Network driver for SMSC91c111 and linked mbufs

Jonas Moberg jonas.moberg at solidsoftware.net
Sat Nov 20 06:48:45 UTC 2004


When tx-ing an ethernet packet that is assembled from linked mbufs - could
ever the mbufs have
an odd length (except for the last mbuf in chain if the complete frame has
an odd length).
Our problem is that the mcf5249 Coldfire chip can not issue external byte
writes so that all accesses
to the network controller must be words.
I can see no way to put single bytes in the tx fifo and then continue
writing words again
on next mbuf boundry.
Re-aligning between a potential "odd mbuf chained to next mbuf" would then
degrade performance.

Solid Software AB
Jonas Moberg





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