Date: Sat, 16 May 2015 12:01:51 -0700 From: Peter Grehan <grehan@freebsd.org> To: Allan Jude <allanjude@freebsd.org> Cc: virtualization@freebsd.org Subject: Re: bhyve code question, pci_virtio_net.c Message-ID: <5557941F.9040608@freebsd.org> In-Reply-To: <55577814.6040202@freebsd.org> References: <55577814.6040202@freebsd.org>
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Hi Allan, > 1) According to the comment, the mac address should be based on the md5 > of the DEVICE name, not the VM name. Which is correct? Which is more > desirable? The comment may not be specific enough - dev name meant /dev/vmm/<devname>, which is the same as the VM name. > Would it make sense to include more unique information in this hash? > like the host's UUID or something, to prevent the chance of more than 1 > VM on the same LAN having the same MAC if they have the same VM Name? Yes: see the discussion at http://lists.freebsd.org/pipermail/freebsd-virtualization/2014-February/002187.html The issue was the changing the algorithm breaks existing Linux VMs which base configuration on MAC addresses. Using the host fixes one issue but creates another in that starting a VM on another host then gives a different MAC. However, there is always the option to set the MAC address manually if you feel there will be issues with collisions, using VMs on different hosts, etc. > 2) Should bhyve instead use the FreeBSD assigned OUI for these MAC > addresses? Yes, though switching to that would have had the same issue with breaking Linux guests. My rough plan to move forward with this is that any new non-virtio NIC emulation will get the FreeBSD OUI and perhaps a different default algorithm. virtio-net will continue to use the existing one, but maybe in the future a "legacy-mac" option will be required to use the old algorithm, and then it can be phased out. Yet another option is an auto-generated MAC is placed in a config file on first boot, ala VMWare. That could be the solution when config file work arrives. later, Peter.
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