diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9b2970f..5e80a9b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2736,10 +2736,16 @@
 				hardware access methods are allowed. Use this
 				if you experience crashes upon bootup and you
 				suspect they are caused by the BIOS.
-		conf1		[X86] Force use of PCI Configuration
-				Mechanism 1.
-		conf2		[X86] Force use of PCI Configuration
-				Mechanism 2.
+		conf1		[X86] Force use of PCI Configuration Access
+				Mechanism 1 (config address in IO port 0xCF8,
+				data in IO port 0xCFC, both 32-bit).
+		conf2		[X86] Force use of PCI Configuration Access
+				Mechanism 2 (IO port 0xCF8 is an 8-bit port for
+				the function, IO port 0xCFA, also 8-bit, sets
+				bus number. The config space is then accessed
+				through ports 0xC000-0xCFFF).
+				See http://wiki.osdev.org/PCI for more info
+				on the configuration access mechanisms.
 		noaer		[PCIE] If the PCIEAER kernel config parameter is
 				enabled, this kernel boot option can be used to
 				disable the use of PCIE advanced error reporting.