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Re: [Qemu-devel] [PATCH] qemu-bridge-helper: force usage of a very high
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] qemu-bridge-helper: force usage of a very high MAC address for the bridge |
Date: |
Fri, 22 Mar 2013 23:09:09 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 |
Il 22/03/2013 22:37, Corey Bryant ha scritto:
> Is it desirable to change a mac address under the covers?
This is the TAP mac address. It is unrelated to the guest's MAC
address. It is a random link-local address, all this patch does is make
it less random.
> 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?
Adding a --macaddr=00:11:... option to force a _particular_ MAC address
could also be useful (if only to help associating guests' MAC addresses
with tap interfaces; the only difference would be the initial 0xFE
byte). But it is not easily done in QEMU because MAC addresses are a
-device option, not a -netdev option.
This patch fixes the real issue that, when the bridge changes MAC
address, there is a small but significant network downtime. See libvirt
commit 6ea90b843eff95be6bcbb49a327656fc6f6445ef for reference.
What would you make it conditional on?
Paolo