Re: [Xen-devel] [PATCH v3 1/7] docs: Improve documentation for dom0= and dom0-iommu=

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Jan 16, 2019 at 09:00:44AM +0000, Andrew Cooper wrote:
> Update to the latest metadata style, and discuss the options more
> completely where appropriate.
> 
> Drop the redundant comment beside parse_dom0_param() - it is already out
> of sync with the main documentation.  Also drop the individual
> documentation for deprecated options which refer to their newer
> versions, for the same reason.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Just one comment.

[...]
> +*   The `map-inclusive` boolean is applicable to x86 PV dom0's, and sets up
> +    identity IOMMU mappings for all non-RAM regions below 4GB except for
> +    unusable ranges, and ranges belonging to Xen.
> +
> +    Typically, some devices in a system use bits of RAM for communication, 
> and
> +    these areas should be listed as reserved in the E820 table and identified
> +    via RMRR or IVMD entries in the APCI tables, so Xen can ensure that they
> +    are identity-mapped in the IOMMU.  However, some firmware makes mistakes,
> +    and this option is a coarse-grain workaround for those errors.
> +
> +    Where possible, finer grain corrections should be made with the `rmrr=`,
> +    `ivrs_hpet=` or `ivrs_ioapic=` command line options.
> +
> +    This option is enabled by default on x86 systems, and invalid on ARM
> +    systems.
> +
> +*   The `map-reserved` functionality is very similar to `map-inclusive`, but 
> is
> +    applicable to both x86 PV and PVH dom0's, and represents a subset of the
> +    correction by only mapping reserved memory regions rather than all 
> non-RAM
> +    regions.

Should you add "This option is enabled by default on x86 systems, and
invalid on ARM systems." here?

Thanks, Roger.

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