ee8388ec69
Some xHCI controllers (such as qemu's emulated xHCI controller) do not correctly handle zero-length packets that are part of a TRB chain. The zero-length TRB ends up being squashed and does not result in a zero-length packet as seen by the device. Work around this problem by marking the zero-length packet as belonging to a separate transfer descriptor. Signed-off-by: Michael Brown <mcb30@ipxe.org>