Re: [PATCH 1/2] IOMMU Identity Mapping Support:iommu_identity_mapping definition

From: Chris Wright
Date: Thu Jun 18 2009 - 14:36:03 EST

* Yu, Fenghua (fenghua.yu@xxxxxxxxx) wrote:
> >>
> >> The first patch defines iommu_identity_mapping varialbe which controls
> >the
> >> identity mapping code and is 0 by default.
> >
> >The only real difference between "pt" and "identity" is hardware support.
> >We should have a single value we don't have to tell users to do different
> >things depending on their hardware (they won't even know what they have)
> >to achieve the same result.
> Technically keeping two separate options in base kernel might be clear and easy to understand. A distro might merge them together or have other usage model.

This pushes burden to distros and users for no obvious gain. Just like
queued invalidation vs. register based's a hardware
detail that users don't really care that much about, they just care
about user visible functionality.

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