After considerable lead up, this corrects the handling of the --mtu option so that it will respect limits imposed by the backend tap layers, correctly accounting for L2 headers. This incorporates the earlier mode setting patches, on which the rest depend. There's been no change in those patches, there just included here for self-containedness. v2: * More static_assert() validation of frame limits in 6/9 * Cosmetic fixups in 6/9 David Gibson (9): conf: Use the same optstring for passt and pasta modes conf: Move mode detection into helper function conf: Detect vhost-user mode earlier packet: Give explicit name to maximum packet size packet: Remove redundant TAP_BUF_BYTES define tap: Use explicit defines for maximum length of L2 frame Simplify sizing of pkt_buf pcap: Correctly set snaplen based on tap backend type conf: Limit maximum MTU based on backend frame size conf.c | 98 +++++++++++++++++++++++++++++++++++++++++--------------- conf.h | 1 + packet.c | 4 +-- packet.h | 3 ++ passt.c | 16 ++------- passt.h | 7 ++-- pcap.c | 46 +++++++++++++------------- tap.c | 44 ++++++++++++++++++++++--- tap.h | 26 +++++++++++++++ util.h | 3 -- 10 files changed, 173 insertions(+), 75 deletions(-) -- 2.48.1