2 files changed, 24 insertions, 0 deletions

diff --git a/sys/boot/common/help.common b/sys/boot/common/help.common
index ad30a33cde819..1a4689b041c92 100644
--- a/sys/boot/common/help.common
+++ b/sys/boot/common/help.common
@@ -277,6 +277,21 @@
 		this option provides a hint as to the actual size of
 		system memory (which will be tested before use).
 
+	set hw.pci.allow_unsupported_io_range=<value>
+
+		Allow the PCI Bridge to pass through an unsupported
+		memory range assigned by the BIOS.
+
+		value is 0 (default) or non-zero to enable.
+
+	set hw.pci.enable_io_modes=<value>
+
+		Enable PCI resources which are left off by some BIOSes
+		or are not enabled correctly by the device driver.
+
+		value is 1 (default), but this may cause problems with
+		some peripherals.  Set to 0 to disable.
+
 ################################################################################
 # Tshow DShow the values of variables
 
diff --git a/sys/boot/common/loader.8 b/sys/boot/common/loader.8
index a32be170bf41c..56faf91eff5bd 100644
--- a/sys/boot/common/loader.8
+++ b/sys/boot/common/loader.8
@@ -422,6 +422,15 @@ are also accepted and indicate kilobytes, megabytes and gigabytes
 respectively.
 An invalid suffix will result in the variable being ignored by the
 kernel.
+.It Va hw.pci.enable_io_modes
+Enable PCI resources which are left off by some BIOSes or are not
+enabled correctly by the device driver.
+Tunable value set to ON (1) by default, but this may cause problems
+with some peripherals.
+.It Va hw.pci_allow_unsupported_io_range
+Allow the PCI bridge to pass through an unsupported memory range
+assigned by the BIOS.
+Tunable value set to OFF (0) by default.
 .It Va kern.maxusers
 Set the size of a number of statically allocated system tables; see
 .Xr tuning 7