[PATCH] powerpc: Document xive=off option

[Michael Neuling]

commit 243e25112d06 ("powerpc/xive: Native exploitation of the XIVE
interrupt controller") added an option to turn off Linux native XIVE
usage via the xive=off kernel command line option.

This documents this option.

Signed-off-by: Michael Neuling <mikey at neuling.org>
---
 Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c45a19d654..ee410d0ef4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5177,6 +5177,15 @@
 			Format:
 			<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
 
+	xive=		[PPC]
+			By default on POWER9 and above, the kernel will
+			natively use the XIVE interrupt controller. This option
+			allows the fallback firmware mode to be used:
+
+			off       Fallback to firmware control of XIVE interrupt
+				  controller on both pseries and powernv
+				  platforms. Only useful on POWER9 and above.
+
 	xhci-hcd.quirks		[USB,KNL]
 			A hex value specifying bitmask with supplemental xhci
 			host controller quirks. Meaning of each bit can be
-- 
2.21.0