SCRATCHBOX 2 README

author: Lauri Leukkunen <lle@rahina.org>
date:   2008-10-20



LICENSING

All files are licensed under GNU LGPL version 2.1 unless specifically 
stated otherwise in the file itself.



GENERAL NOTICE

This is no longer only development code, it is expected to work.
If it doesn't, please file a bug at: https://bugs.freedesktop.org/


INSTALLATION

You need git to work with sbox2, get it from http://git.or.cz/.

Clone the scratchbox 2 repository:
$ git clone git://anongit.freedesktop.org/git/sbox2
or if behind a corporate firewall, use http:
$ git clone http://anongit.freedesktop.org/git/sbox2.git

For x86_64 hosts Scratchbox 2 automatically builds both i386
and x86_64 versions of libsb2.so, for this reason you need
to have the necessary 32bit support libs available (libc6-dev-i386,
lib32gcc1 & co. on debian).

To build SB2:

$ cd sbox2
$ ./autogen.sh
$ make install prefix=$HOME/sb2

You need Qemu for cpu-transparency. As of 2009-03, qemu-0.10.1 seems to work
pretty well.

Latest Qemu can be retrieved with: 

$ git clone git://git.savannah.nongnu.org/qemu.git
$ cd qemu
$ ./configure --prefix=$HOME/sb2 --target-list=arm-linux-user
$ make && make install

If you're targeting ARM you can get a good toolchain from CodeSourcery:
http://www.codesourcery.com/gnu_toolchains/arm/download.html

Notice! Old Scratchbox 1 toolchains don't work with SB2.

To use sb2 you need to get a rootfs for your target and put it into
some useful directory, alternatively you can copy the necessary files
into right places from your toolchain. The essential thing is that
sb2 needs FHS compliant target directory structure to work.

From a codesourcery toolchain, you can find the "seed" target rootfs contents
from arm-2008q3/arm-none-linux-gnueabi/libc, simply copy that to the buildroot.

To complete sb2 target setup:

$ mkdir $HOME/buildroot
$ cd $HOME/buildroot
$ cp -a $HOME/arm-2008q3/arm-none-linux-gnueabi/libc/{lib,etc,usr} .
$ $HOME/sb2/bin/sb2-init my_target arm-none-linux-gnueabi-gcc

That will automatically generate a working target config for the compiler
given on the command line and run sb2-build-libtool script to get you a
nice working libtool for your compiler. If the sb2-build-libtool part
fails for some reason (incorrect http proxy or something similar), you
can always run it manually later.

At this point you can simply run sb2:

$ $HOME/sb2/bin/sb2

sb2-init made this target your default if you had no prior sb2 targets
configured. To change the default use sb2-config -d your_target.

Perhaps adding $HOME/sb2/bin to your PATH is also a good idea, put
this in your $HOME/.bashrc:
-- snip --
export PATH=$PATH:$HOME/sb2/bin
-- snip --

After that you can run sb2 easily from anywhere and it'll just do its magic.
Continuing the above examples, here's how to compile and run a simple
hello-world program:

$ sb2 gcc -o hello hello.c
$ sb2 ./hello
Hello, World!


MAEMO DEVELOPMENT

The Maemo SDK+ project at http://maemo-sdk.garage.maemo.org/ provides
everything you need to develop for Maemo using SB2.


DIAGNOSING PROBLEMS WITH SB2

Sometimes everything does not work as expected, so it is good to know
how to locate problems (typically problems are related to misconfigured
mapping rules). Scratchbox 2 can produce extensive logs about all
operations, but it does not do so by default. So the first step is
to enable logging: Use the "-d" or "-L <level>" options of "sb2".

For example,

$ sb2 -L info dpkg-buildpackage -rfakeroot -d

will produce a log of most important actions that were performed by
"dpkg-buildpackage" and all subprocesses started by it. The log will
be created under ~/sb2_logs/ (The above command will also print out the
exact name and location of the logfile.)

The produced logfile can be quite huge, especially when using the higher
logging levels. A logfile analyzer script, sb2-logz, can be used to extract
essentials like error and warning messages and path mapping actions from
the logged information; log level 'info' in enough for anything that
sb2-logz needs. Higher logging levels ('debug', etc) are mostly useful
only for developers of scratchbox 2.

Another useful helper tool is "sb2-show", an utility which can be used to 
test path and command mapping rules while scratchbox 2 is active.

For example,

$ sb2-show path /etc/apt

$ sb2-show -b apt-get path /etc/apt

will show how the /etc/apt database has been mapped. The latter command
uses "apt-get" as the name of the calling program (the results may
be different depending on mapping mode, name of the calling program, etc)

sb2-show can also be used to see how parameters to certain processes will
be modified:

$ sb2-show exec gcc foo.c

shows which "gcc" would be started inside the sb2 session, together with
the actual, possibly modified, arguments. The result depends on how sb2 
was configured (see notes about sb2-init above)


KNOWN ISSUES

1. Dmalloc is utterly and completely incompatible with Scratchbox 2.
2. Performance is not as good as it could be.
3. Memory leaks exist, but they have not posed significant problems
   so far.

-- 
That's all folks, enjoy!