Document hw.bce.msi_enable tunable.

Approved by:	re (blanket)

share/man/man4/bce.4

@@ -28,7 +28,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 9, 2007
+.Dd June 24, 2007
 .Dt BCE 4
 .Os
 .Sh NAME
@@ -140,6 +140,17 @@ HP NC370T Multifunction Gigabit Server Adapter
 .It
 HP NC370i Multifunction Gigabit Server Adapter
 .El
+.Sh SYSCTL VARIABLES
+The following variables are available as both
+.Xr sysctl 8
+variables and
+.Xr loader 8
+tunables:
+.Bl -tag -width indent
+.It Va hw.bce.msi_enable
+Whether or not MSI support is enabled in the driver.
+The default value is 1.
+.El
 .Sh DIAGNOSTICS
 .Bl -diag
 .It "bce%d: PCI memory allocation failed!"