Gentoo Prefix Bootstrap Process for FreeBSD

1.  Bootstrapping on FreeBSD

Introduction

An off-the-shelf FreeBSD system is bare. Very bare. Whoever thought that bootstrapping on Solaris was hard, FreeBSD makes it even harder. The lack of tools like bash and perl requires some pre-bootstrapping prior to the actual bootstrapping process. Alternatively you can install a Bash through the ports system. If you bootstrap on FreeBSD, make sure the development tools are installed, which include system headers and a compiler. This bootstrap guide was tested on a FreeBSD 8.2 x86_64 system. Other architectures should not differ too much. Feel free to try it out on other configurations and post to the gentoo-alt mailing list for additional help.

Bootstrapping

As prerequisite, you need a GCC compiler, the GNU binutils linker and system headers, such that source code can be compiled into working executables. Sufficient versions are installed by installing the developer tools.

The first step is to choose a path to install into. We refer to this path as "prefix path", stored in the variable EPREFIX. A suggestion for your prefix path is $HOME/gentoo. Whatever you chose, make sure you set it in your environment:

$ export EPREFIX="$HOME/gentoo"
        

Next, add the following paths in your soon to be prefix to your PATH environment. $EPREFIX/bin, $EPREFIX/usr/bin, $EPREFIX/tmp/bin and $EPREFIX/tmp/usr/bin. Adding these paths makes sure that they will be available later on in the process.

$ export PATH="$EPREFIX/usr/bin:$EPREFIX/bin:$EPREFIX/tmp/usr/bin:$EPREFIX/tmp/bin:$PATH"
        

Now the path is set, start with downloading the bootstrap script from http://overlays.gentoo.org/proj/alt/browser/trunk/prefix-overlay/scripts/bootstrap-bash.sh?format=txt and http://overlays.gentoo.org/proj/alt/browser/trunk/prefix-overlay/scripts/bootstrap-prefix.sh?format=txt. From the directory where the bootstrap scripts were stored execute the following commands:

$ chmod 755 bootstrap-bash.sh bootstrap-prefix.sh
$ mkdir $EPREFIX/tmp
$ ./bootstrap-bash.sh $EPREFIX/tmp
$ ./bootstrap-prefix.sh $EPREFIX tree
$ ./bootstrap-prefix.sh $EPREFIX/tmp make
$ ./bootstrap-prefix.sh $EPREFIX/tmp wget
$ ./bootstrap-prefix.sh $EPREFIX/tmp sed
$ ./bootstrap-prefix.sh $EPREFIX/tmp python
$ ./bootstrap-prefix.sh $EPREFIX/tmp coreutils8
$ ./bootstrap-prefix.sh $EPREFIX/tmp findutils3
$ ./bootstrap-prefix.sh $EPREFIX/tmp tar22
$ ./bootstrap-prefix.sh $EPREFIX/tmp patch9
$ ./bootstrap-prefix.sh $EPREFIX/tmp gawk
$ ./bootstrap-prefix.sh $EPREFIX portage
        

The script will setup the $EPREFIX directory, download a portage tree snapshot, unpack it and download and install portage. Afterwards it will try to setup some sane defaults. We continue with a little hack necessary for a successful bootstrap.

Let your shell take notice of all just installed programs.

$ hash -r
        

We continue adding some necessary tools which will deal with many errors and warnings you might see during emerging.

$ emerge --oneshot sed
        

Next, we emerge the bash shell Portage heavily relies on. The same holds for wget, the download manager. Since its dependencies cannot be compiled at this stage, we ignore those for the moment.

$ emerge --oneshot --nodeps bash (avoid deps that ship scripts with shebang /bin/sh)
$ emerge --oneshot --nodeps xz-utils
$ emerge --oneshot --nodeps "<wget-1.13.4-r1" (until we fix #393277)
        

Now, we will emerge a compiler which will use the GNU linker. This is a requirement for many packages that follow in the bootstrap process, in particular Perl. The packages to emerge include the baselayout package. Some, if not many, scripts and tools within a Gentoo system assume the availability of the baselayout package for all communication using the Gentoo colour scheme.

$ emerge --oneshot --nodeps baselayout-prefix
$ emerge --oneshot --nodeps m4
$ emerge --oneshot --nodeps flex
$ emerge --oneshot --nodeps bison
$ emerge --oneshot --nodeps binutils-config
$ emerge --oneshot --nodeps binutils
$ emerge --oneshot --nodeps gcc-config
$ emerge --oneshot --nodeps "=gcc-4.2*"
        

We continue getting more tools in our Prefix. We no longer ignore dependencies all the time, so a lot of packages will be emerged at this stage. Slowly our Prefix gets more robust as we progress here.

$ emerge --oneshot perl
$ emerge --oneshot coreutils
$ emerge --oneshot findutils
$ emerge --oneshot tar
$ emerge --oneshot grep
$ emerge --oneshot patch
$ emerge --oneshot gawk
$ emerge --oneshot make
$ emerge --oneshot --nodeps file
$ emerge --oneshot --nodeps eselect
$ emerge --oneshot pax-utils
        

Now we have a good bunch of programs that Portage needs, we can replace the bootstrapped Portage by a properly installed one, using Portage itself. Also here a few dependencies are first emerged, such as the language Portage is written in: python. We need to temporarily tell Portage that the bootstrapped Portage can be overwritten.

$ env FEATURES="-collision-protect" emerge --oneshot portage
        

Now we have emerged everything we bootstrapped before, we remove the temporary directory and its use as it is no longer necessary.

$ rm -Rf $EPREFIX/tmp/*
$ hash -r
        

Before we do any further merges, we are going to update our tree. Updating the tree is done using:

$ emerge --sync
        

Next, we let Portage emerge all packages that complete a system install that we eventually need to finalise this Prefix installation.

$ USE=-git emerge -u system
        

Now is a good time to set the preferences for our soon to be Prefix. This includes customisations such as general USE-flags, CFLAGS and MAKEOPTS in $EPREFIX/etc/make.conf. Be conservative with CFLAGS! Note that the code below is an example, and is meant for inspiration only.

$ echo 'USE="unicode nls"' >> $EPREFIX/etc/make.conf
$ echo 'CFLAGS="-O2 -pipe"' >> $EPREFIX/etc/make.conf
$ echo 'CXXFLAGS="${CFLAGS}"' >> $EPREFIX/etc/make.conf
        

Since we have everything in place for a self-catered rebuild, we can start the final stage to install the Prefix system. This final stage recompiles everything in the system, but now all packages can be compiled with tools from the Prefix, instead of those from the host system.

$ emerge -e system
        

After system has emerged successfully, your Prefix will be set up properly, and you can emerge the whichever tools you choose from the Prefix tree.

Using the Prefix

To use your bootstrapped prefix environment, you best start a shell from the prefix, such that your path and other environment variables are set correctly. To facilitate in this, a small helper script can be created by the bootstrap script.

$ cd $EPREFIX/usr/portage/scripts
$ ./bootstrap-prefix.sh $EPREFIX startscript
        

After running this, a script startprefix will be present in $EPREFIX. You can freely move the script to e.g. your homedir for convenience. Running the script will drop you into a prefix shell, where for example emerge is directly at your disposal. Enjoy your prefix!

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