Re: [PATCH] Document x86-64 iommu kernel parameters
From: Randy Dunlap
Date: Tue Oct 02 2007 - 22:23:45 EST
On Tue, 2 Oct 2007 21:34:13 -0400 Jeff Garzik wrote:
>
> 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.
"iommu" is listed in Documentation/x86_64/boot-options.txt
along with more x86_64-specific boot options.
A few other arches do something similar...
> 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.
> -
---
~Randy
-
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