of alloc_pkb() exhaustion when e.g. an iSCSI-booted DOS session is left
idle for a long time at the C:\ prompt and builds up a huge packet
backlog.

skb_tailroom().  Add pkb_headroom().

(which will need us to wait for TX completions).

Added debug autocolourisation to netdevice.c

This will allow us to implement RX quotas.

to the PIC while it was disabled.

function prefix "undinet_" and the variable name "undinic" in undinet.c,
so that we can reserve the variable name "undi" for a struct undi_device.

The idea is that we preserve the Etherboot 5.4 convention that the "UNDI"
code refers to our using an underlying UNDI stack, while the "PXE" code
refers to our providing a PXE API.

UNDI_GET_INFORMATION calls into drivers/net/undi.c.  undi_probe() now
gets given a pxe_device representing a PXE stack that has been loaded
into memory but not initialised in any way.

Handle failures in undi_open() properly.

lying about in memory, not for loading from ROM), and UNDI net driver.