git: if_tap: Handle 'SIOCSIFMTU' ioctl directly to support MTU > 1500

Aaron LI aly at
Sun Nov 10 03:14:15 PST 2019

commit 4bbbd8e095115472b0d89a15256367db0ab2cc86
Author: Aaron LI <aly at>
Date:   Sun Nov 10 17:28:52 2019 +0800

    if_tap: Handle 'SIOCSIFMTU' ioctl directly to support MTU > 1500
    Add the SIOCSIFMTU ioctl handling directly to tap(4) permitting it to
    have its MTU set higher than 1500 (ETHERMTU).  Its new limit is now
    65535 as enforced by 'ifhwioctl()' in 'if.c'.
    This allows a tap(4) device to be added to a bridge, which requires all
    interface members to have the same MTU, with an interface configured for
    jumbo frames.  QEMU may now connect to a network via tap(4) without
    requiring the real interface to have its MTU set to 1500 or lower.
    Also bump __DragonFly_version.
    Obtained-from: FreeBSD (revision 189866)

Summary of changes:
 sys/net/tap/if_tap.c | 8 +++++++-
 sys/sys/param.h      | 3 ++-
 2 files changed, 9 insertions(+), 2 deletions(-)

DragonFly BSD source repository

More information about the Commits mailing list