[Qemu-discuss] any restriction on the guest mac addr when using tap networking?

[Xeslaro]

  when using tap networking, everything works perfectly when i don't specify a 
specific mac addr for the guest, but when i choose a mac addr for the 
guest(just 6 random bytes), strange things happen. sometimes it works, 
sometimes it don't.
  when i dump the traffic on the tap device, the host obviously could receive 
the packets sent by the guest because it answers all the arp requests, but the 
guest seems couldn't receive anything at all as it still send arp request and 
the packets it received is zero from the status of the connection(it's running 
windows xp).
  so i guess there's some limitation about the mac addr i could assign to the 
guest? i googled but didn't find anything related.
  p.s. the host is running linux 3.9.0-rc6+ and qemu-1.4.1