The Xen network backend (xen-netback) suffered from a regression
between upstream Linux kernels 3.18 and 4.2 inclusive, which would
cause packet reception to fail unless at least 18 receive buffers were
available.  This bug was fixed in kernel commit 1d5d485 ("xen-netback:
require fewer guest Rx slots when not using GSO").

Work around this bug in affected versions of xen-netback by providing
the requisite 18 receive buffers.

Reported-by: Taylor Schneider <tschneider@live.com>
Tested-by: Taylor Schneider <tschneider@live.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

Relicense files for which I am the sole author (as identified by
util/relicense.pl).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Signed-off-by: Michael Brown <mcb30@ipxe.org>