On Mon, Nov 12, 2012 at 12:49 PM, Lin Ma <l...@suse.com> wrote: >>>> Paolo Bonzini <pbonz...@redhat.com> 11/12/12 7:27 PM >>> > > Il 12/11/2012 12:18, Daniel P. Berrange ha scritto: >>> > QEMU doesn't check if there are mac collisions when adding nics. >>> > It causes mac address collisions in guest if adding the nics which >>> > include existing physical address. >>> > This patch fixes the issue. >> I understand the issue, but are there not use cases where it is >> reasonable to have multiple NICs with the same MAC address ? To >> me this kind of policy enforcement belongs at a higher level in >> the mgmt stack. > >>>>I agree. > > Yes, Users won't intentionally add multiple NICs with the same MAC address. > But what if there is typos in command-line or upper layer applications pass > a conflicting mac option to qemu? > We can't fully trust other applications to do this. So qemu shouldn't depend > on other applications for the verifying mac. > No matter upper layer applications verify mac or not, qemu should check the > mac itself again to ensure the correctness.
It's perfectly okay to use the same MAC address on multiple cards from a hardware emulation perspective (which is the scope of QEMU). Higher level tools can perform this check if they want this policy. Stefan
