Messages in this thread | | | Date | Mon, 22 Sep 2008 18:31:09 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH] AMD IOMMU: revert "x86, AMD IOMMU: honor iommu=off instead of amd_iommu=off" |
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On Tue, Sep 23, 2008 at 12:25:23AM +0900, FUJITA Tomonori wrote: > I don't think that users need to have iommu=calgary parameter to use > calgary IOMMU by default. If you enable CONFIG_CALGARY_IOMMU, > CALGARY_IOMMU_ENABLED_BY_DEFAULT is also enabled by default. If a > kernel finds calgary IOMMU, the kernel uses it by default. > > It's also consistent with how SWIOTLB. Users don't need iommu=soft > parameter to enable SWIOTLB. A kernel enables SWIOTLB automatically > when necessary.
Yes. The parameters are usefull if a user wants to enable a specific IOMMU implementation. The user could be an IOMMU developer testing changes in a special implementation the kernel would not choose by default on his machine. I like Ingo's idea here. Lets do boths, implementing iommu=$type to force a specific iommu implementation and $(type)_iommu=off to disable one.
> Well, this is the problem about the IOMMUs parameters. The IOMMUs > parameters are too complicated for everyone.
Not so complicated that they can't be understood. But if you have a proposal how the command line parameters for iommus may look like, send it. I like join that discussion about the interface.
Joerg
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