On 08/11/18 18:30, Wei Liu wrote:
> On Thu, Nov 08, 2018 at 06:29:05PM +0000, Andrew Cooper wrote:
>> On 08/11/18 18:08, Wei Liu wrote:
>>> 0e2c886ef ("xen: decouple HVM and IOMMU capabilities") provided a
>>> truth table for what `xl info` would report. In order to make the
>>> table work xen will need to report its PV capability.
>>>
>>> Replace cap_directio with cap_pv in libxl IDL. It is safe to do so
>>> because cap_directio has never been released. Revert to use
>>> cap_hvm_directio to mark the availability of IOMMU, to save us from
>>> providing a compatibility layer.
>>>
>>> Don't bump sysctl version number because we've already done so.
>>>
>>> Signed-off-by: Wei Liu <[email protected]>
>> In principle, I think this is fine. However, some observations.
>>
>> Looking more closely at the matrix, we've got:
>>
>> pv hvm iommu flags in xl info
>> 0 0 x n/a
>> 0 1 0 hvm
>> 0 1 1 hvm hvm_directio
>> 1 0 0 NIL
>> 1 0 1 directio
>> 1 1 0 hvm
>> 1 1 1 hvm hvm_directio directio
>>
>> Wouldn't it make more sense to have pv and pv_directio, even if only as
>> the end user visible string?
> That would be fine by me. I didn't do it because I couldn't figure out
> the difference between virt_caps and xen_caps.
The answer is most probably "it grew organically and without any real
design in the past".
~Andrew
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