From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:35183) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UJ9eJ-0005Qf-2Z for qemu-devel@nongnu.org; Fri, 22 Mar 2013 17:37:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UJ9eG-0005zx-V7 for qemu-devel@nongnu.org; Fri, 22 Mar 2013 17:37:19 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:46096) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UJ9eG-0005za-Od for qemu-devel@nongnu.org; Fri, 22 Mar 2013 17:37:16 -0400 Received: from /spool/local by e39.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 22 Mar 2013 15:37:13 -0600 Message-ID: <514CCF04.4070408@linux.vnet.ibm.com> Date: Fri, 22 Mar 2013 17:37:08 -0400 From: Corey Bryant MIME-Version: 1.0 References: <1363971468-21154-1-git-send-email-pbonzini@redhat.com> In-Reply-To: <1363971468-21154-1-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] qemu-bridge-helper: force usage of a very high MAC address for the bridge List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org, qemu-stable@nongnu.org On 03/22/2013 12:57 PM, Paolo Bonzini wrote: > 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 > --- > qemu-bridge-helper.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/qemu-bridge-helper.c b/qemu-bridge-helper.c > index 287bfd5..6a0974e 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); > Is it desirable to change a mac address under the covers? I know you mentioned that libvirt does something like this already. Also it seems like this might be better if it was optional. qemu-bridge-helper can take command line options like this: -net tap,helper="/usr/local/libexec/qemu-bridge-helper --br=br0" Perhaps adding a --macaddr option is a better approach? -- Regards, Corey Bryant