Ansis Atteka c1b164d70c util: centralize tap device MAC address 1st byte "0xFE" modification ... When a tap device for a domain is created and attached to a bridge, the first byte of the tap device MAC address is set to 0xFE, while the rest is set to match the MAC address that will be presented to the guest as its network device MAC address. Setting this high value in the tap's MAC address discourages the bridge from using the tap device's MAC address as the bridge's own MAC address (Linux bridges always take on the lowest numbered MAC address of all attached devices as their own). In one case within libvirt, a tap device is created and attached to the bridge with the intent that its MAC address be taken on by the bridge as its own (this is used to assure that the bridge has a fixed MAC address to prevent network outages created by the bridge MAC address "flapping" as guests are started and stopped). In this case, the first byte of the mac address is *not* altered to 0xFE. In the current code, callers to virNetDevTapCreateInBridgePort each make the MAC address modification themselves before calling, which leads to code duplication, and also prevents lower level functions from knowing the real MAC address being used by the guest. The problem here is that openvswitch bridges must be informed about this MAC address, or they will be unable to pass traffic to/from the guest. This patch centralizes the location of the MAC address "0xFE fixup" into virNetDevTapCreateInBridgePort(), meaning 1) callers of this function no longer need the extra strange bit of code, and 2) bitNetDevTapCreateBridgeInPort itself now is called with the guest's unaltered MAC address, and can pass it on, unmodified, to virNetDevOpenvswitchAddPort. There is no other behavioral change created by this patch.		2012-03-02 16:04:00 -05:00
..
bridge_driver.c	util: centralize tap device MAC address 1st byte "0xFE" modification	2012-03-02 16:04:00 -05:00
bridge_driver.h	network: Fix typo	2011-07-26 19:57:34 +08:00
default.xml