Re: [PATCH] docs: fusa: Add dom0less domain configuration requirements

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Ayan and Julien,

> On 16 Nov 2024, at 10:57, Julien Grall <julien@xxxxxxx> wrote:
> 
> Hi Ayan,
> 
> On 15/11/2024 18:53, Ayan Kumar Halder wrote:
>>>> +Assign vCPUs from CPU pool
>>>> +--------------------------
>>>> +
>>>> +`XenSwdgn~arm64_assign_vcpus_cpu_pool~1`
>>>> +
>>>> +Description:
>>>> +Xen shall assign vCPUs to a domain from a CPU pool.
>>> 
>>> Same remark about the wording. You create a domain with N vCPUs and 
>>> *assign* a CPU pool to a domain.
>> Ok, so all the previous 3 requirements can be merged into
>> Xen shall create a domain with N vCPUs and assign a CPU pool to a domain.
>> Or
>> Xen shall create a domain with N vCPUs.
> 
> I think this one is better because it is not mandatory for the user to select 
> a CPU pool and you will have it ...
> 
>> (which of the two looks better to you if we keep the next requirement ?)
> 
> ... by the next one.
> 
>> Comments:
>> Here N is determined by the device tree configuration provided by the user.
>>> You also assign pCPU to a CPU pool.
>>> 
>>> But I am not sure about if this requirement is actually necessary given ...
>>> 
>>>> +
>>>> +Rationale:
>>>> +
>>>> +Comments:
>>>> +
>>>> +Covers:
>>>> + - `XenProd~static_domains_configuration~1`
>>>> +
>>>> +Specify CPU pool scheduler
>>>> +--------------------------
>>>> +
>>>> +`XenSwdgn~arm64_specify_cpu_pool_scheduler~1`
>>>> +
>>>> +Description:
>>>> +Xen shall assign a CPU pool scheduler to a domain.
>>> 
>>> ... you have th is one.
>> So, we can keep it as it is.
>>> 
>>>> +
>>>> +Rationale:
>>>> +
>>>> +Comments:
>>>> +
>>>> +Covers:
>>>> + - `XenProd~static_domains_configuration~1`
>>>> +
>>>> +Assign virtual UART
>>>> +-------------------
>>>> +
>>>> +`XenSwdgn~arm64_assign_virtual_uart~1`
>>>> +
>>>> +Description:
>>>> +Xen shall assign a virtual UART to a domain.
>>> 
>>> Are we talking about the virtual PL011 or the fake emulation of the real 
>>> UART we do?
>> virtual PL011.
> 
> Is it possible to specify it in the market requirements?
> 
> [...]
> 
>>>> +
>>>> +Static VM definition
>>>> +--------------------
>>>> +
>>>> +`XenMkt~static_vm_definition~1`
>>>> +
>>>> +Description:
>>>> +Xen shall support specifying resources for a domain.
>>> 
>>> Compare to the other requirements, this is quite a vague. Should we list 
>>> the resources?
>> The list of resources depends on what the user has provided in the device 
>> tree configuration.
>> But the requirement is correct as it is. Xen allows direct assignment of 
>> devices to domains (ie passthrough).
>> How do you want to write it ?
> 
> This is probably a better question for Bertrand. I don't know how market 
> requirements are usually described. I was making a comparison with the other 
> where you explicitely listed the expected resources (e.g. CPU, Memory, 
> device).

I definitely agree with Julien here, this requirement is not clear as 
"resources" is not specified or defined.
I would highly suggest to be more specific by listing what we mean by resources 
and maybe even split this requirement in several to make testing and linking 
easier.

Cheers
Bertrand

> 
> Cheers,
> 
> -- 
> Julien Grall