[PATCH] Document x86-64 iommu kernel parameters

From: Jeff Garzik
Date: Tue Oct 02 2007 - 21:34:24 EST



Signed-off-by: Jeff Garzik <jgarzik@xxxxxxxxxx>
---
After having to go figure out what some of these means, I figured I
would save others the trouble.

Some of these are "best guess" based on a quick scan of the code, so it
certainly needs a sanity review before going upstream.

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4d175c7..8afea9b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -763,6 +763,30 @@ and is between 256 and 4096 characters. It is defined in the file

inttest= [IA64]

+ iommu=option[,option..] [X86-64]
+ off Disable IOMMU.
+ force Unconditionally enable IOMMU.
+ noforce Disable IOMMU and IOMMU merging, by default.
+ biomerge Unconditionally enable IOMMU, IOMMU merging,
+ and set BIO IOMMU vmerge boundary to 4096.
+ panic Panic on IOMMU overflow.
+ nopanic Do not panic on IOMMU overflow.
+ merge Unconditionally enable IOMMU, IOMMU merging.
+ nomerge Disable IOMMU merging.
+ forcesac Force single address cycle (SAC, 32-bit).
+ allowdac Permit dual address cycle (DAC, 64-bit).
+ nodac Forbid dual address cycle (DAC, 64-bit).
+ soft Enable swiotlb.
+ calgary Use Calgary IOMMU.
+
+ (GART-only options follow...)
+ <NNN> Specify size of remapping area.
+ fullflush Disable optimizing flushing strategy.
+ nofullflush Enable optimizing flushing strategy.
+ noagp Use entire aperture, AGP isn't using it.
+ noaperture Disable aperture fixups / hole init.
+ memaper=<N> malloc an aperture of order N.
+
io7= [HW] IO7 for Marvel based alpha systems
See comment before marvel_specify_io7 in
arch/alpha/kernel/core_marvel.c.
-
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