From: Lars Kurth <lars.kurth@citrix.com>
To: George Dunlap <George.Dunlap@citrix.com>, Sarah Newman <srn@prgmr.com>
Cc: StefanoStabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
Andrew Cooper <Andrew.Cooper3@citrix.com>,
Julien Grall <julien.grall@arm.com>,
Jan Beulich <JBeulich@suse.com>,
Ian Jackson <Ian.Jackson@citrix.com>,
Xen-devel <xen-devel@lists.xenproject.org>,
Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [Xen-devel] Terminology for "guest" - Was: [PATCH] docs/sphinx: Introduction
Date: Tue, 13 Aug 2019 08:46:35 +0000 [thread overview]
Message-ID: <0B276C27-7682-4D8C-9B40-DB246826B11C@citrix.com> (raw)
In-Reply-To: <E4C0136D-9D42-4174-942E-EB6365CB11A1@citrix.com>
On 13/08/2019, 09:43, "George Dunlap" <George.Dunlap@citrix.com> wrote:
> On Aug 13, 2019, at 3:59 AM, Sarah Newman <srn@prgmr.com> wrote:
>
> On 8/12/19 8:01 AM, Andrew Cooper wrote:
>> On 12/08/2019 15:53, George Dunlap wrote:
>>> On 8/8/19 10:13 AM, 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. I
>>>> actually thought we renamed everything in Xen from Dom0 to hwdom to
>>>> avoid the confusion.
>>>>
>>>> I also would rather avoid to treat "dom0" as not a guest. In normal
>>>> setup this is a more privilege guest, in other setup this may just be a
>>>> normal guest (think about partitioning).
>>> A literal guest is someone who doesn't live in the building (or work in
>>> the buliding, if you're in a hotel). The fact that the staff cleaning
>>> rooms are restricted in their privileges doesn't make them guests of the
>>> hotel.
>>>
>>> The toolstack domain, the hardware domain, the driver domain, the
>>> xenstore domain, and so on are all part of the host system, designed to
>>> allow you to use Xen to do the thing you actually want to do: Run guests.
>>>
>>> And it's important that we have a word that distinguishes "domains that
>>> we only care about because they make it possible to run other domains",
>>> and "domains that we actually want to run". "guest / host" is a natural
>>> terminology for these.
>>>
>>> We already have the word "domain", which includes dom0, driver domains,
>>> toolstack domains, hardware domains, as well as guest domains. We don't
>>> need "guest" to be a synonym for "domain".
>> So...
>> Please can someone propose wording simple, clear wording for what
>> "guest" means.
>
> A potentially untrusted domain.
But wouldn’t that include both driver domains and stubdomains?
I think the definition you provided looks good and is also along the lines which how most people use it
Lars
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next prev parent reply other threads:[~2019-08-13 8:46 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 19:41 [Xen-devel] [PATCH] docs/sphinx: Introduction Andrew Cooper
2019-08-07 22:49 ` Hans van Kranenburg
2019-08-07 23:25 ` Andrew Cooper
2019-08-08 6:22 ` Jan Beulich
2019-08-08 8:43 ` [Xen-devel] Terminology for "guest" - Was: " Andrew Cooper
2019-08-08 9:04 ` Jan Beulich
2019-08-08 9:13 ` Julien Grall
2019-08-08 10:30 ` Andrew Cooper
2019-08-08 10:49 ` Jan Beulich
2019-08-08 11:22 ` Rich Persaud
2019-08-12 14:53 ` George Dunlap
2019-08-12 15:01 ` Andrew Cooper
2019-08-13 2:59 ` Sarah Newman
2019-08-13 8:43 ` George Dunlap
2019-08-13 8:46 ` Lars Kurth [this message]
2019-08-13 19:58 ` Sarah Newman
2019-08-08 9:49 ` Roger Pau Monné
2019-08-12 15:36 ` [Xen-devel] " George Dunlap
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