Felipe Contreras

Extract them:
sudo tar -xf /tmp/sb/scratchbox-core-1.0.14-i386.tar.gz -C /opt
sudo tar -xf /tmp/sb/scratchbox-libs-1.0.14-i386.tar.gz -C /opt
sudo tar -xf /tmp/sb/scratchbox-devkit-qemu-0.10.0-0sb5-i386.tar.gz -C /opt
sudo tar -xf /tmp/sb/scratchbox-toolchain-cs2007q3-glibc2.5-arm7-1.0.12-9-i386.tar.gz -C /opt

Setup scratchbox, and add your user:
sudo /opt/scratchbox/run_me_first.sh
sudo /opt/scratchbox/sbin/sbox_adduser $USER yes

You'll need to re-login to be in the sbox group and have proper permissions:
sudo su $USER

target

Finally, setup an armv7 target (you can have multiple targets inside scratchbox):
/opt/scratchbox/tools/bin/sb-conf setup armv7 --force --compiler="cs2007q3-glibc2.5-arm7" --devkits="qemu" --cputransp="qemu-arm-sb"
/opt/scratchbox/tools/bin/sb-conf select armv7
/opt/scratchbox/tools/bin/sb-conf install armv7 --clibrary --devkits --fakeroot --etc

That's it, you have scratchbox setup I explicitly mentioned all the commands, but instead you can run this script that I wrote.

start

Before running scratchbox you'll need to do some steps as root:
echo 0 > /proc/sys/vm/vdso_enabled
echo 4096 > /proc/sys/vm/mmap_min_addr
/opt/scratchbox/sbin/sbox_ctl start

And then as user:
/opt/scratchbox/login

This will get you to this screen:

Welcome to Scratchbox, the cross-compilation toolkit!

Use 'sb-menu' to change your compilation target.
See /scratchbox/doc/ for documentation.

[sbox-armv7: ~] > 

Now if you want to cross-compile GLib, you do it as in your PC:
./configure && make install

Much easier, now scratchbox does all the magic

Scratchbox 2

Scratchbox 1 serves it's purpose, but there are many corner-cases where things get overly complicated so people came up with a much more elegant approach: Scratchbox 2.

In sb1 you need to login to a target (e.g. armv7, armv6, fremantle, diablo, etc.) in order to do anything, you can use only one target at a time, and each target is independent, in order to share tools between targets you need a devkit. Also, toolchains must be packaged in a special way.

In sb2, you don't login, you can setup any toolchain easily, you can use multiple targets at the same time, and you can configure it to do pretty much anything you want.

QEMU

sb2 doesn't include QEMU, you must have it already, this is how I compile it:
git clone git://git.savannah.nongnu.org/qemu.git
cd qemu
git checkout -b stable v0.10.5
./configure --prefix=/opt/qemu --target-list=arm-linux-user
make install

sbox2

Compile and install like this:
git clone git://anongit.freedesktop.org/git/sbox2
cd sbox2
./configure --prefix=/opt/sb2
make install

Add sb2 to the PATH:
export PATH=/opt/sb2/bin:$PATH

target

Now it's time to configure a target, I have a CodeSourcery toolchain installed on /opt/arm-2008q3, so:
cd /opt/arm-2008q3/arm-none-linux-gnueabi/libc/
sb2-init -c /opt/qemu/bin/qemu-arm armv7 /opt/arm-2008q3/bin/arm-none-linux-gnueabi-gcc

You don't need to log-in, just prefix your commands with sb2 to do the magic:
sb2 ./configure --prefix=/opt/arm/

If you want to use a different target just use the -t option:
sb2 -t armv8 ./configure --prefix=/opt/arm/

How cool is that?