K 10
svn:author
V 3
jhb
K 8
svn:date
V 27
2016-08-26T20:15:22.858670Z
K 7
svn:log
V 676
Enable I/O MMU when PCI pass through is first used.

Rather than enabling the I/O MMU when the vmm module is loaded,
defer initialization until the first attempt to pass a PCI device
through to a guest.  If the I/O MMU fails to initialize or is not
present, than fail the attempt to pass a PCI device through to a
guest.

The hw.vmm.force_iommu tunable has been removed since the I/O MMU is
no longer enabled during boot.  However, the I/O MMU support can be
disabled by setting the hw.vmm.iommu.enable tunable to 0 to prevent
use of the I/O MMU on any systems where it is buggy.

Reviewed by:	grehan
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D7448

END