Re: busybox replacement idea

[Alan Barrett <apb%cequrux.com@localhost>]

On Fri, 24 Aug 2012, Jeremy C. Reed wrote:
> Depending on the configuration, there may be up to 310 commands 
> all contained in one binary [with busybox].
>
> NetBSD already has a similar feature: /rescue/foo. This 
> crunchgen solution has around 150 commands.

I believe that crunchgen has no fixed limits to the number of 
commands.

> We should be able to just copy the existing simple and short 
> src/rescue/ infrastructure to create the more complete 
> replacement.

Yes, of course.  However, this often requires adding a few 
conditional lines to the Makefile for the program to be built, and 
if you want to omit some features from the crunched version of the 
program then you have to add conditional code to the source of the 
program itself.

For example, the build infrastructure for /rescue instructs 
crunchgen to set SMALLPROG in the environment; sbin/init/Makefile 
uses that to change the CPPFLAGS and libraries; and 
sbin/init/init.c uses the preprocessor definitions to 
conditionally exclude some features.

> Then we should allow building this for a non-NetBSD target 
> system. Any suggestions or examples on how to build rescue for a 
> non-NetBSD target system?

This is the only non-trivial part.

> We may not be as small, but three benefits may be 1) user 
> friendly commands; 2) nice license for proprietary use (There 
> have been license violations reported for busybox); and 3) nice 
> promotion of NetBSD.
>
> Any thoughts on this?

It's not difficult to have more than two levels of "the 
full-featured command" and "a smaller version omitting some 
features".  Different invocations of crunchgen can set different 
environment variables (akin to the existing SMALLPROG variable) 
which can be fed through the Makefils and CPPFLAGS to achieve 
finer control over what features to include or exclude.  (For 
example, I use crunchgen to build images in which init is 
full-featured, whereas the standard NetBSD /rescue contains an 
init with reduced functionality.)

--apb (Alan Barrett)