Re: [PATCH] Document x86-64 iommu kernel parameters

[Randy Dunlap <randy.dunlap@oracle.com>]

On Tue, 2 Oct 2007 21:34:13 -0400 Jeff Garzik wrote:

> 
> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
> ---
> 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