Re: Rust: kernel vs user-space

Am 04.09.24 um 17:21 schrieb Bob Bishop:
> Hi,
> 
>> On 4 Sep 2024, at 15:37, Stefan Esser <se@FreeBSD.org> wrote:
>>
>> Am 04.09.24 um 11:52 schrieb Mark Delany:
>>> On 04Sep24, David Chisnall apparently wrote:
>>>> There are lots of control-plane things that I'd love to see
>>>> written mostly in Lua,
>>> It was remiss of me to not mention Lua given that it's already in the project.
>>> Yet another language which could make life easier, more productive and more accessible in
>>> user-land.
>>> I'm not suggesting for an instant that any of these programs need rewriting, but one could
>>> imagine that if commands like ifconfig, route, arp, ndp, ipfw (that is, programs which
>>> take a lot of user input and do a lot of data manipulation but aren't super-critical on
>>> the performance front) were written in a more accessible language, then it might attract
>>> new developers without disenfranchising the core C developers.
>>
>> Here is ldconfig in LUA, written more than 2 years ago, for example:
>>
>> https://github.com/stesser/ldconfig/blob/main/ldconfig.lua
> 
> And this is better than C because ...?
> 
> (Asking for a friend :-)

There had been a request for an architecture independent implementation
that works on all FreeBSD releases and architectures.

The LUA run-time has been available in FreeBSD for a long time, and it
is a stable platform suitable for the implementation of commands that
operate on text and might take advantage of features like associative
storage. It is a "safe" implementation since memory is automatically
managed, which reduces the risk of memory management errors (but we
have to trust the LUA interpreter to be free of such issues, instead).

I have not made this version available for review (but instead updated
the C version to work with hints files of either byte order). But this
code is much simpler than the C version it replaces, and it could easily
be extended to, e.g., prepare hints files in chroot environments or in
images prepared for an architecture with a (possibly) different byte order.

And it is not only independent of the byte order and portable over all
architectures, but also independent of the FreeBSD version.

The LUA version is much shorter and easier to understand (if you know
LUA), but one reason not to propose it for inclusion in FreeBSD is that
there are many more developers that know how to work on the C version
than on the LUA version.

David and Mark have mentioned LUA, and there is little LUA code in the
base system, currently (mostly the loader). I'd like to see LUA being
used for more functionality that is not time critical, and since the LUA
language has been very stable over time (other than many other interpreted
languages), it is unlikely that a LUA script will not work on a later
FreeBSD release (it only depends on a working flua and possibly some
LUA include files).

Anyway, this is off-topic for the discussion about rust, other than
that LUA is a language that is not affected by many bugs that are
typical for programs written in C.

Best regards, STefan