Bug 112702

Summary:	[em] em driver doesn't use MSI on MSI capable device
Product:	Base System	Reporter:	Arthur Hartwig <arthur.hartwig>
Component:	kern	Assignee:	jfv
Status:	Closed FIXED
Severity:	Affects Only Me	CC:	sbruno
Priority:	Normal	Keywords:	IntelNetworking
Version:	Unspecified
Hardware:	Any
OS:	Any

Description Arthur Hartwig 2007-05-16 08:30:04 UTC

FreeBSD 7 built a few weeks ago used MSI on two MSI capable interfaces
(82572 chips). 

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.

Comment 1 Remko Lodder freebsd_committer

2007-05-16 15:19:27 UTC

Responsible Changed
From-To: freebsd-bugs->jfv

Over to maintainer.

Comment 2 Sean Bruno freebsd_committer

2015-06-29 17:51:06 UTC

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.