towards a good embedded userland cross-build system (was: Re: _G_config.his not installed)

[Dan Kegel <dank at kegel dot com>]

Robert Schwebel wrote:
> > When I was debugging my gcc/glibc cross build script
> > (http://kegel.com/crosstool), I found that glibc-2.2.5 thought it was
> > doing a native compile if it could run the target executables on the
> > build host.  Maybe 2.2.4 is similar?
>
> I'll try it. The problem is that the effect is non-deterministic.
> Sometimes it just works, then without obvious reasons it does not work
> any more. 

You have my sympathy.  This kind of problem is what drove me to
using a simple shell script rather than a Makefile, and doing everything
clean from scratch every time.

> When I started with the toolchain stuff in the beginning I had a shell
> script as well but it turned out that the complex dependencies between
> the various packets can be better solved with Makefiles. 

Just wait until you try to support gcc-3.3 and glibc-2.3.2 -- you
may change your mind!  Some files have to be installed twice, kind of, I think.
I'm not sure if that kind of dependency can be expressed.
But maybe I'm just pessimistic.

> So I started
> looking around for what other people have done. Most projects (Emdebsys:
> cml2 problems all over the place; Gentoo: database not separable from
> the target system; RPM, Debian: dito; uCLinux: archives bundled with the
> framework, too large for initial download) didn't work fine for an
> Embedded System scenario (no space on the target for databases, highly
> configurable, very small packet size for initial download), so I ended
> up with Erik's buildroot.  As he didn't want to have patches for a
> kconfig frontend I basically copied his framework (also to make it
> easier to steal packets later), added the kconfig stuff and things
> started evolving. 

I badly need something to build a whole userspace, and I went through
the same list of build systems.  I also checked Rock Linux (too complex).
Another promising one is http://pkgsrc.org; they don't support cross-building
yet, but they are looking at it, and supposedly have several hundred
packages cross-building already.  I will definitely have a look at your framework.

> I don't know if you already had a look at the framework, probably it's
> better to wait until I've made the next release. It also might be an
> idea to look at which "direction" of porting might be better - PTXdist
> just using crosstools or porting it over. I somehow hope that you like
> the concept and port your script into the framework ;) 

I'm sorely tempted to keep the gcc/glibc build process separate from
any framework.  Even when I finally settle on a userland build framework
that uses Make or whatever, it may have a prerequisite that you have
already got a toolchain installed and working.  Melding the two
seems like a bad match somehow -- I want totally correct dependencies,
and am pretty sure I can do that using Makefilesu
for all of userland except for the toolchain.
- Dan

--
Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045