The 82546GB chip does not work with OpenVSwitch, while similar chips do. It works with the old vlan/bridge code. In the attachement is a script to reproduce the problem and the output of ethregs.
Here is a summary of the results:
ping ethregs ping ethregs
80003ES2 + - + -
80003ES2_iomem + + + +
80003ES2_iomem_run2 + + + +
82546GB + + - +
82546GB_iomem + + - +
82546GB_iomem_run2 - + - +
Maybe it is an initialization issue of the card.
For more details see my mails on the e1000-devel mailing list.