Prioritizing and documenting libbsd development goals (was: libbsd updates)

[Christian MAUDERER]

On 2023-01-25 10:05, Sebastian Huber wrote:
> On 25.01.23 10:01, Christian MAUDERER wrote:
>> On 2023-01-25 09:59, Sebastian Huber wrote:
>>> On 25.01.23 09:52, Christian MAUDERER wrote:
>>>> OK. Updated list based on Thomas and Sebastians feedback:
>>>>
>>>>  From highest to lowest priority:
>>>>
>>>> - Real time capabilities: No hard real time requirements for libbsd 
>>>> core, but we have to make sure that it doesn't have a (relevant) 
>>>> negative impact on other subsystems.
>>>>
>>>> - Maintainability: How easy is it for the people doing the main 
>>>> maintenance tasks to do that work.
>>>>
>>>> - Transparency: How easy it is to understand the code? Relevant for 
>>>> extending and debugging.
>>>>
>>>> - Code and RAM sizes (or other hardware requirements): Whether we 
>>>> meet the minimum hardware requirements.
>>>>
>>>> - Modularity: How well and easy the system can be adapted to target 
>>>> applications. Have only few official ways to enable / disable 
>>>> modules in the subsystem.
>>>>
>>>> - Performance: Whether libbsd performs well enough in the typical 
>>>> use cases.
>>>>
>>>> Any more suggestions for the order? Like I said, I would like to 
>>>> integrate that to the libbsd documentation as goals for that 
>>>> subsystem that can be used to evaluate different approaches for 
>>>> implementing something. Would be good to have some more feedback 
>>>> from others too.
>>>>
>>>> For example: I prioritized maintainability over transparency. That 
>>>> means that we might choose a solution that's simpler to maintain but 
>>>> makes it harder to integrate new modules. Is that OK?
>>>>
>>>> Similar the order of modularity and code / RAM size can be an issue: 
>>>> Most of the time these should go well together. But it's quite 
>>>> possible that some nice modular configuration options need extra 
>>>> code compared to less nice methods. From my point of view we target 
>>>> embedded systems where code and RAM size is more important. But I'm 
>>>> not sure that this is the focus for everyone else too?
>>>
>>> I would not give the minimum RAM size such a low priority. libbsd 
>>> used to work on systems with 16MiB. If you add new things which 
>>> require additional 4MiB even if you don't use the stuff, then you 
>>> simply kick out systems which used to work with libbsd.
>>>
>>
>> So no lower than modularity. Should it be higher than transparency or 
>> maintainability? From the earlier comments I don't expect that it 
>> should be higher than (core) real time capability.
>>
>> What would be your preferred order?
> 
> Lets say you are a user of libbsd version X. Then you want to update to 
> version X + 1. Version X + 1 no longer works on your system, because 
> libbsd needs more RAM than you have. Would you really give this user an 
> answer like this:
> 
> Sorry, maintainability and transparency is more important for us, so 
> please stick to version X.
> 

Regarding code / RAM size versus maintainability:

Maintainability does also include the upgrade process to newer base 
versions of FreeBSD. So if it's more important that code size doesn't 
increase compared to how easy libbsd is to maintain, that can make 
upgrades to newer FreeBSD versions _very_ difficult. I don't think that 
would be a good trade.

Code size versus transparency (how easy it is for someone new to start 
development and how easy it is to debug through the code) is a bit more 
opinion based. The current order is from what I have understood in the 
discussion. I don't have a problem to re-order these.

Note: I'm OK with most orders as long as most of the maintainers can 
agree on one.
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