Contributions: Adding New Devices

Contributions: Adding New Devices

[Federico Vaga]

Hello,

I can't find this information on the website, so here I am.

I developed a QEMU device that virtualises a PCI card that we widely use at CERN.
But this card is only used at CERN.

Clearly, having CERN specific devices in QEMU does not help much the qemu
community, hence I maintain an internal QEMU fork.

But, I was wondering what is the QEMU policy about contributions that are known to be
used only by a handful of people (one organization in this case)? Are they accepted?

Second. Even if you will not accept such contribution, are you anyway open to reviews?
I'm not QEMU expert, so it would be nice if someone can review what I wrote.

--
Federico Vaga

Re: Contributions: Adding New Devices

[Connor Kuehl]

On 6/30/21 7:01 AM, Federico Vaga wrote:
> Hello,
> 
> I can't find this information on the website, so here I am.
> 
> I developed a QEMU device that virtualises a PCI card that we widely use at CERN.
> But this card is only used at CERN.
> 
> Clearly, having CERN specific devices in QEMU does not help much the qemu
> community, hence I maintain an internal QEMU fork.
> 
> But, I was wondering what is the QEMU policy about contributions that are known to be
> used only by a handful of people (one organization in this case)? Are they accepted?

Your first instinct is correct that it's unlikely that the community
will be able to maintain a device if it's really so niche as to only
be used at your organization.

However, if you do decide to try to upstream it, it could only help
your chances if you or some of your colleagues agreed to maintain it
for the QEMU community. This mainly involves adding an entry to the
MAINTAINERS file where, if accepted, the expectation is that you'll
be reachable within reason to review patches, make pull requests,
help discuss bugs in the subsystem, etc.

Sorry I don't have a concrete "yes" or "no" for you; but I'd recommend
giving it a shot if you have the time.

Connor

Re: Contributions: Adding New Devices

[Philippe Mathieu-Daudé]

On 7/1/21 9:48 PM, Connor Kuehl wrote:
> On 6/30/21 7:01 AM, Federico Vaga wrote:
>> Hello,
>>
>> I can't find this information on the website, so here I am.
>>
>> I developed a QEMU device that virtualises a PCI card that we widely use at CERN.

What kind of device is it? You might be surprise to see later someone
else interested in what your specific device does and reuse part of it.

Is the datasheet/documentation public?

Can you provide test? (so it doesn't bitrot while we do code changes
unrelated to your device code)

>> But this card is only used at CERN.
>>
>> Clearly, having CERN specific devices in QEMU does not help much the qemu
>> community, hence I maintain an internal QEMU fork.
>>
>> But, I was wondering what is the QEMU policy about contributions that are known to be
>> used only by a handful of people (one organization in this case)? Are they accepted?
> 
> Your first instinct is correct that it's unlikely that the community
> will be able to maintain a device if it's really so niche as to only
> be used at your organization.
> 
> However, if you do decide to try to upstream it, it could only help
> your chances if you or some of your colleagues agreed to maintain it
> for the QEMU community. This mainly involves adding an entry to the
> MAINTAINERS file where, if accepted, the expectation is that you'll
> be reachable within reason to review patches, make pull requests,
> help discuss bugs in the subsystem, etc.

As Connor said (although you probably won't have to worry about
pull request burden, other will help you while you ramp up).
Beside, code only usable by you shouldn't have a lot of traffic,
so maintenance shouldn't take too much.

Regards,

Phil.

Re: Contributions: Adding New Devices

[Federico Vaga]

Thanks for your answers

On Fri, Jul 02, 2021 at 12:07:49AM +0200, Philippe Mathieu-Daudé wrote:
>On 7/1/21 9:48 PM, Connor Kuehl wrote:
>> On 6/30/21 7:01 AM, Federico Vaga wrote:
>>> Hello,
>>>
>>> I can't find this information on the website, so here I am.
>>>
>>> I developed a QEMU device that virtualises a PCI card that we widely use at CERN.
>
>What kind of device is it? You might be surprise to see later someone
>else interested in what your specific device does and reuse part of it.

It's really specific to our particle accelerators facility. This card receives
packets over a custom network, which payloads contain information about the
accelerator "setup", or synchronization information.

>Is the datasheet/documentation public?
>
>Can you provide test? (so it doesn't bitrot while we do code changes
>unrelated to your device code)

Ideally, with some work, yes.

>>> But this card is only used at CERN.
>>>
>>> Clearly, having CERN specific devices in QEMU does not help much the qemu
>>> community, hence I maintain an internal QEMU fork.
>>>
>>> But, I was wondering what is the QEMU policy about contributions that are known to be
>>> used only by a handful of people (one organization in this case)? Are they accepted?
>>
>> Your first instinct is correct that it's unlikely that the community
>> will be able to maintain a device if it's really so niche as to only
>> be used at your organization.
>>
>> However, if you do decide to try to upstream it, it could only help
>> your chances if you or some of your colleagues agreed to maintain it
>> for the QEMU community. This mainly involves adding an entry to the
>> MAINTAINERS file where, if accepted, the expectation is that you'll
>> be reachable within reason to review patches, make pull requests,
>> help discuss bugs in the subsystem, etc.
>
>As Connor said (although you probably won't have to worry about
>pull request burden, other will help you while you ramp up).
>Beside, code only usable by you shouldn't have a lot of traffic,
>so maintenance shouldn't take too much.

I could try to submit it, at least to get a review. Then, for us it's not a
problem to apply a patch on to of QEMU to have our virtual device.