Re: [Xen-devel] [ARM] Native application design and discussion (I hope)

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 08/05/17 19:31, Stefano Stabellini wrote:
> On Mon, 8 May 2017, George Dunlap wrote:
>> On 05/05/17 20:28, Stefano Stabellini wrote:
>>> On Fri, 5 May 2017, Andrii Anisov wrote:
>>>> Hello Stefano,
>>>>
>>>> On 24.04.17 21:08, Stefano Stabellini wrote:
>>>>> Stubdomains (stubdoms in short) are small domains, each running a single
>>>>> application. Typically they run unikernels rather than a full fledged
>>>>> operating system. A classic example is QEMU stubdoms on x86: one QEMU
>>>>> stubdoms is started for each regular guest domain. Each QEMU stubdom
>>>>> instance provides emulation for one guest - it runs one instance of
>>>>> QEMU.
>>>> I'm wondering if there are any examples of practical usage of stub domains
>>>> with ARM?
>>>
>>> Good question. I don't think so: there have been practical examples of
>>> unikernels running on Xen on ARM, but not stubdoms, because we haven't
>>> needed to run large emulation pieces yet.
>>
>> So often when we say "stub domains" we mean specifically, "devicemodel
>> stub domains".  But there are many other stub domains for other
>> purposes.  You can run xenstored in a stubdomain rather than in dom0,
>> for instance; I think this probably already works on ARM.  I believe
>> that the PV vTPM architecture also has one vTPM "worker" per guest,
>> along with a "global" domain to control the physical TPM and multiplex
>> it over the various vTPMs.
> 
> TPM is an x86 concept, but xenstored stubdom is possible.

A few years ago I'd have said ACPI was an x86 concept as well. :-)  But
my point was mainly to give examples to Andrii of other ways stubdomains
were used.

 -George


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