FreeBSD 7 built a few weeks ago used MSI on two MSI capable interfaces
The recent substantial changes to emdriver have broken emdriver's use of MSI.
Inspection of if_em.c shows em_attach() calls em_allocate_pci_resources()
which for a 82572 based NIC to use MSI ends up requiring the bus.type field
in the adapter structure to be set to e1000_bus_type_pci_express. However
the bus type is not initialised until the call to e1000_get_bus_info() which
is called AFTER em_attach() calls em_allocate_pci_resources().
I have been investigating the use of MSI to avoid interrupt sharing in a
new system with a significant number of PCI express NICs.
Over to maintainer.
There has been significant changes to the em(4) driver since this bug was reported. If MSI handling is still broken for these cards on the 10.2r release, please open a new ticket.