From 226ecabfbd410c7b2041385ea4b6f083a09ce8a2 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 22 Mar 2013 17:57:48 +0100 Subject: [PATCH] qemu-bridge-helper: force usage of a very high MAC address for the bridge Linux uses the lowest enslaved MAC address as the MAC address of the bridge. Set MAC address to a high value so that it does not affect the MAC address of the bridge. Changing the MAC address of the bridge could cause a few seconds of network downtime. Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini Message-id: 1363971468-21154-1-git-send-email-pbonzini@redhat.com Signed-off-by: Anthony Liguori --- qemu-bridge-helper.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/qemu-bridge-helper.c b/qemu-bridge-helper.c index 287bfd5e38..6a0974eb48 100644 --- a/qemu-bridge-helper.c +++ b/qemu-bridge-helper.c @@ -367,6 +367,24 @@ int main(int argc, char **argv) goto cleanup; } + /* Linux uses the lowest enslaved MAC address as the MAC address of + * the bridge. Set MAC address to a high value so that it doesn't + * affect the MAC address of the bridge. + */ + if (ioctl(ctlfd, SIOCGIFHWADDR, &ifr) < 0) { + fprintf(stderr, "failed to get MAC address of device `%s': %s\n", + iface, strerror(errno)); + ret = EXIT_FAILURE; + goto cleanup; + } + ifr.ifr_hwaddr.sa_data[0] = 0xFE; + if (ioctl(ctlfd, SIOCSIFHWADDR, &ifr) < 0) { + fprintf(stderr, "failed to set MAC address of device `%s': %s\n", + iface, strerror(errno)); + ret = EXIT_FAILURE; + goto cleanup; + } + /* add the interface to the bridge */ prep_ifreq(&ifr, bridge); ifindex = if_nametoindex(iface);