Re: Mac-Address uniqueness

Avi Kivity
2007-06-01T06:26:16Z

H. Peter Anvin wrote:
> Axel Kittenberger wrote:
>
>> Unfortunally all machines detect the same ethernet address
>> '52:54:00:12:34:56'. Which you can guess what i means, networking comes
>> and goes whatever machine last the ethernet address got hold of from the
>> gateway. I tried specifing an ethernet-adress with "-net
>> nic,macaddr=$MAC" but this also didn't work through.
>>
>> For now I just hardseted the mac in all machines to 52:54:00:12:34:57,
>> 52:54:00:12:34:58 and so on.
>>
>>
>
> This is a Qemuism. I always thought it was dumb, but I guess Qemu
> wanted reproducibility over everything.
>
> IMNSHO it would have been much better to default to a random value
> (meaning that all except the bottom 2 bits of the first octet are
> random, those bits should be set to 10 binary.)
>
>

That tends to consume dhcp leases quickly, if you start guests often (as
I do). Also, some distributions use the mac address as a key for naming
interfaces; if it changes, the guest gets confused

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.