Using linux kernel 2.4.20 I was getting the
message "Warning: kfree_skb on hard IRQ c01a1eab"
many times. Searching the internet for a solution I found
http://www.tux.org/hypermail/linux-tulip/2001-
Nov/0072.html
So I changed line 694 of kaweth.c from
dev_kfree_skb(skb);
to
dev_kfree_skb_irq(skb);
and the error went away.
JonH