Cross compiling on AMD64 – the teaser

Cross compiling is the act of compiling for one platform (e.g. i386) when on another (e.g. AMD 64).
Why is this interesting to me? I have an AMD 64 3000+ with 1GB of RAM running on an
ASUS A8V Deluxe¹.
It’s acting as my gateway right now. Needless to say, it is very under utilized.

Recently, I’ve been consolidating my machine room and getting rid of older, slower machines.
As a result, the services provided by these boxes have been moved onto faster boxes.
One of these services is building world. I don’t like building world on my laptop.
It’s slow and too much wear and tear on a laptop drive can’t be good for it. 😉

The solution, Build world on your fast box, install on your slow box
I’ve been doing that since early 2001, nearly 6 years. However, that was when everything I owned ran
the same version of FreeBSD. But now I have FreeBSD 4.11 and FreeBSD 6.0-RC1 running here. I might also
have FreeBSD 5.4 running soon (as a testing platform for the best backup solution.
I want my AMD 64 to run in amd64 mode, not i386. And I want it to build for all those targets.

¹ – I erroneously reported my mainboard as an
ASUS ASUS A8V-E Deluxe
when I first published this article. And, for what it’s worth, this machine is no longer my gateway.
– 29 December 2005

Solutions I thought about and discarded

When I first thought about this, I had a few bright ideas, all discarded.

multiple machines: Nope. I didn’t like this one. Too much to look after and I’d like to do
this all on one machine
multi-boot: I thought about multi-booting the system. Each time I wanted to build for 5.x, I’d
boot the system into 5.x, build, and then install. That would work. But it’s ugly.
I could only install for one version at a time, and builds would happen serially instead
of in parallel. It would also prevent me from running other services on the box, such
as a database server. I can’t be developing FreshPorts
with a database server that’s not up all the time.
jails: I could install a jail under 6.0 and run 4.x or 5.x in that jail. That would work. But there
are overheads associated with a jail. It’s like having another machine to look after.

emulation

I could run a virtual machine on each box and run the appropriate OS within that machine and then
build from there. Sorry, but that’s too much like running jails and I already discarded that idea.
In addition, there was some question as to performance. Yes, I’m just building world here, but
I’d like to do it quickly.

So what solution did I choose?

I went with something very simple. It’s fast, it’s efficient, and it works. Well, it works so far.
I have managed to build world and a kernel. I have not tested the output, but the preliminary results
are very promising.

I hope to get to this final testing this weekend and have something more than just a teaser for you
next week.

Cross compiling on AMD64 – the teaser