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Date: Tue, 29 Sep 2009 11:24:45 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [RfC PATCH 1/3] net: macaddr tweaks.
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To: Markus Armbruster <armbru@redhat.com>
Cc: qemu-devel@nongnu.org

>> +void qemu_macaddr_default_if_unset(macaddr_t macaddr)
>> +{
>> +    macaddr_t zero = { 0,0,0,0,0,0 };
>> +
>> +    if (memcmp(macaddr, zero, sizeof(zero)) != 0)
>> +        return;
>> +    macaddr[0] = 0x52;
>> +    macaddr[1] = 0x54;
>> +    macaddr[2] = 0x00;
>> +    macaddr[3] = 0x12;
>> +    macaddr[4] = 0x34;
>> +    macaddr[5] = 0x56;
>> +}
>> +
>
> This will get us the same default MAC address for all NICs, won't it?
> The old code provides a different default for each NIC.
>
> Simply increment the default whenever it is used?

Would be an option.  Doesn't fully match the old behavior though.

Old behavior is to use 0x56 + nic index (i.e. nd_table index) for the 
last byte, so nic #1 allways has 0x57, no matter whenever for nic #0 a 
default was specified or not.

The problem we have here is that the nics created via -device don't have 
a nd_table entry and thus no nic index.  We have a related issue with 
pxe boot (-boot n,o,p,q == boot first,second,third,fourth nic).

Didn't have a good idea (yet) how to address that.

>> +typedef uint8_t macaddr_t[6];
>
> Reserved identifier (any POSIX header).  Do we care?

We should prrobably qemu-ify it to something like MACAddr anyway.

cheers,
   Gerd