Re: Why do we need lua in-tree again? Yet another call for actual evidence, please. (was Re: Moving Lua source codes)

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

   Date: Thu, 17 Oct 2013 19:16:16 -0300
   From: Lourival Vieira Neto <lourival.neto%gmail.com@localhost>

   Lua is a tool, not an end in itself. I think that you are formulating
   a chicken-and-egg problem: we need the basic support for then having
   applications, and we need applications for then having basic support.

This is not a chicken-and-egg problem.  You can make an experimental
kernel with Lua support and make an experimental application in Lua,
all before anything has to be committed to HEAD[*].  Then you can show
that the application serves a useful function, has compelling benefits
over writing it in C, and can offer confidence in robustness.

[*] You could do this in a branch, you could do this in a private Git
repository, or you could even just do this in a local CVS checkout
(since kernel Lua requires no invasive changes, right?).

   That is not about needing, but it is about supporting a certain
   kind of agile development, prototyping, customization and
   experimentation in the NetBSD kernel (how could it be hurtful?).

Prototyping and experimentation is great!  Show examples!  What hurts
is getting bitrotten code that nobody actually maintains or uses (when
was the last Lua update in src?) and provides a new Turing machine
with device access in the kernel for attack vectors.

   [1] https://github.com/dergraf/PacketScript

   [2] http://www.pdsw.org/pdsw12/papers/grawinkle-pdsw12.pdf

In the two links you gave, I found precisely five lines of Lua code,
buried in the paper, and those five lines seemed to exist only for the
purpose of measuring how much overhead Lua adds to the existing pNFS
code or something.