Re: [PATCH v1 3/4] dt-bindings: Add bindings for vmgenid

Landge, Sudan
2024-03-20T12:16:25Z

Hi Krzysztof,

The recipient were removed by mistake. I have added them all back and
fixed the email client to send mail in the right format. Sorry about that.
I'll revert after I have done more analysis and better data to explain.
Thank you for the quick feedback again.

Thanks and regards,
Sudan

On 20/03/2024 10:24, Krzysztof Kozlowski wrote:
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>
>
>
> On 20/03/2024 11:17, Landge, Sudan wrote:
>>
>> On 19/03/2024 15:28, Krzysztof Kozlowski wrote:
>>> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
>>>
>>>
>
> Why did you remove all the people from CC list?
> >>>
>>> On 19/03/2024 15:32, Sudan Landge wrote:
>>>> Virtual Machine Generation ID driver was introduced in commit af6b54e2b5ba
>>>> ("virt: vmgenid: notify RNG of VM fork and supply generation ID"), as an
>>>> ACPI only device.
>>> That's not a valid rationale. Second today... we do not add things to
>>> bindings just because someone added some crazy or not crazy idea to Linux.
>>>
>>> Bindings represent the hardware.
>>>
>>> Please come with real rationale. Even if this is accepted, above reason
>>> is just wrong and will be used as an excuse to promote more crap into
>>> bindings.
>>
>> Thank you for the quick review.
>>
>> I will add more details to the problem we are trying to fix with an
>> updated cover letter
>>
>> but to summarize the problem briefly:
>>
>> Firecracker is a minimalist feature hypervisor and we do not have ACPI
>> support
>>
>> for ARM yet. The vmgenid devicetree support looked a better option because
>>
>> supporting ACPI on ARM means supporting UEFI which adds a lot of complexity.
>
> That does not convince me. Amount of work for you is not making virtual
> stuff real hardware. Come with some other discoverable protocol - you
> have full control of both sides of this thing.
>
>>
>>> A nit, subject: drop second/last, redundant "bindings". The
>>> "dt-bindings" prefix is already stating that these are bindings.
>>> See also:
>>> https://elixir.bootlin.com/linux/v6.7-rc8/source/Documentation/devicetree/bindings/submitting-patches.rst#L18
>>>
>>> Please use subject prefixes matching the subsystem. You can get them for
>>> example with `git log --oneline -- DIRECTORY_OR_FILE` on the directory
>>> your patch is touching.
>> Got it, thanks.
>>>> Add a devicetree binding support for vmgenid so that hypervisors
>>>> can support vmgenid without the need to support ACPI.
>>> Devicetree is not for virtual platforms. Virtual platform can define
>>> whatever interface they want (virtio, ACPI, "VTree" (just invented now)).
>> Sorry for my lack of experience in this area. I took reference of virtio
>> devices when I
>>
>> uploaded the patch. We would still like to support vmgenid via a
>> devicetree so I'll
>>
>> revert with a new approach.
>
> There are other solutions, I think. This was discussed already multiple
> times.
>
>>
>>>> Signed-off-by: Sudan Landge<sudanl@amazon.com>
>>>> ---
>>>> .../devicetree/bindings/vmgenid/vmgenid.yaml | 57 +++++++++++++++++++
>>> No, you do not get your own hardware subsystem. Use existing ones.
>>
>> Got it. The changes are related to the "rng" subsystem so I'll rethink
>> if that is the
>>
>> right place for this and revert.
>
> Your wrapping is odd. Please use some decent email client.
>
> Anyway, I am not discussing topics semi-private. Keep all maintainers in
> loop.
>
> Best regards,
> Krzysztof
>