On Aug 8, 2019, at 06:49, Jan Beulich <jbeul...@suse.com> wrote:
>
>> On 08.08.2019 11:13, Julien Grall wrote:
>> Hi Jan,
>>
>>> On 08/08/2019 10:04, Jan Beulich wrote:
>>>> On 08.08.2019 10:43, Andrew Cooper wrote:
>>>>> On 08/08/2019 07:22, Jan Beulich wrote:
>>>>>> On 07.08.2019 21:41, Andrew Cooper wrote:
>>>>>> --- /dev/null
>>>>>> +++ b/docs/glossary.rst
>>>>>> @@ -0,0 +1,37 @@
>>>>>> +Glossary
>>>>>> +========
>>>>>> +
>>>>>> +.. Terms should appear in alphabetical order
>>>>>> +
>>>>>> +.. glossary::
>>>>>> +
>>>>>> + control domain
>>>>>> + A :term:`domain`, commonly dom0, with the permission and
>>>>>> responsibility
>>>>>> + to create and manage other domains on the system.
>>>>>> +
>>>>>> + domain
>>>>>> + A domain is Xen's unit of resource ownership, and generally has
>>>>>> at the
>>>>>> + minimum some RAM and virtual CPUs.
>>>>>> +
>>>>>> + The terms :term:`domain` and :term:`guest` are commonly used
>>>>>> + interchangeably, but they mean subtly different things.
>>>>>> +
>>>>>> + A guest is a single virtual machine.
>>>>>> +
>>>>>> + Consider the case of live migration where, for a period of
>>>>>> time, one
>>>>>> + guest will be comprised of two domains, while it is in transit.
>>>>>> +
>>>>>> + domid
>>>>>> + The numeric identifier of a running :term:`domain`. It is
>>>>>> unique to a
>>>>>> + single instance of Xen, used as the identifier in various APIs,
>>>>>> and is
>>>>>> + typically allocated sequentially from 0.
>>>>>> +
>>>>>> + guest
>>>>>> + See :term:`domain`
>>>>>
>>>>> I think you want to mention the usual distinction here: Dom0 is,
>>>>> while a domain, commonly not considered a guest.
>>>>
>>>> To be honest, I had totally forgotten about that. I guess now is the
>>>> proper time to rehash it in public.
>>>>
>>>> I don't think the way it currently gets used has a clear or coherent set
>>>> of rules, because I can't think of any to describe how it does get used.
>>>>
>>>> Either there are a clear and coherent (and simple!) set of rules for
>>>> what we mean by "guest", at which point they can live here in the
>>>> glossary, or the fuzzy way it is current used should cease.
>>>
>>> What's fuzzy about Dom0 not being a guest (due to being a part of the
>>> host instead)?
>> Dom0 is not part of the host if you are using an hardware domain.
>
> It's still the control domain then, and hence still part of the host.
With disaggregation and dom0less (how might we describe that term in the
intro?) for edge/embedded Xen systems, there could be a mode where the control
domain has never had privilege over the domain that handles the physical TPM,
or the provider of the virtual TPM:
https://lists.gt.net/xen/devel/557782
Rich
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