319 lines
12 KiB
Markdown
Executable File
319 lines
12 KiB
Markdown
Executable File
# pi-gen
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_Tool used to create the raspberrypi.org Raspbian images_
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## Dependencies
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pi-gen runs on Debian based operating systems. Currently it is only supported on
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either Debian Stretch or Ubuntu Xenial and is known to have issues building on
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earlier releases of these systems. On other Linux distributions it may be possible
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to use the Docker build described below.
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To install the required dependencies for pi-gen you should run:
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```bash
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apt-get install coreutils quilt parted qemu-user-static debootstrap zerofree pxz zip \
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dosfstools bsdtar libcap2-bin grep rsync xz-utils file git curl
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```
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The file `depends` contains a list of tools needed. The format of this
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package is `<tool>[:<debian-package>]`.
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## Config
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Upon execution, `build.sh` will source the file `config` in the current
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working directory. This bash shell fragment is intended to set needed
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environment variables.
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The following environment variables are supported:
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* `IMG_NAME` **required** (Default: unset)
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The name of the image to build with the current stage directories. Setting
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`IMG_NAME=Raspbian` is logical for an unmodified RPi-Distro/pi-gen build,
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but you should use something else for a customized version. Export files
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in stages may add suffixes to `IMG_NAME`.
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* `APT_PROXY` (Default: unset)
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If you require the use of an apt proxy, set it here. This proxy setting
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will not be included in the image, making it safe to use an `apt-cacher` or
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similar package for development.
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If you have Docker installed, you can set up a local apt caching proxy to
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like speed up subsequent builds like this:
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docker-compose up -d
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echo 'APT_PROXY=http://172.17.0.1:3142' >> config
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* `BASE_DIR` (Default: location of `build.sh`)
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**CAUTION**: Currently, changing this value will probably break build.sh
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Top-level directory for `pi-gen`. Contains stage directories, build
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scripts, and by default both work and deployment directories.
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* `WORK_DIR` (Default: `"$BASE_DIR/work"`)
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Directory in which `pi-gen` builds the target system. This value can be
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changed if you have a suitably large, fast storage location for stages to
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be built and cached. Note, `WORK_DIR` stores a complete copy of the target
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system for each build stage, amounting to tens of gigabytes in the case of
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Raspbian.
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**CAUTION**: If your working directory is on an NTFS partition you probably won't be able to build. Make sure this is a proper Linux filesystem.
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* `DEPLOY_DIR` (Default: `"$BASE_DIR/deploy"`)
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Output directory for target system images and NOOBS bundles.
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* `DEPLOY_ZIP` (Default: `1`)
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Setting to `0` will deploy the actual image (`.img`) instead of a zipped image (`.zip`).
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* `USE_QEMU` (Default: `"0"`)
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Setting to '1' enables the QEMU mode - creating an image that can be mounted via QEMU for an emulated
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environment. These images include "-qemu" in the image file name.
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* `FIRST_USER_NAME` (Default: "pi" )
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Username for the first user
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* `FIRST_USER_PASS` (Default: "raspberry")
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Password for the first user
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* `WPA_ESSID`, `WPA_PASSWORD` and `WPA_COUNTRY` (Default: unset)
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If these are set, they are use to configure `wpa_supplicant.conf`, so that the raspberry pi can automatically connect to a wifi network on first boot.
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* `ENABLE_SSH` (Default: `0`)
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Setting to `1` will enable ssh server for remote log in. Note that if you are using a common password such as the defaults there is a high risk of attackers taking over you RaspberryPi.
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* `STAGE_LIST` (Default: `stage*`)
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If set, then instead of working through the numeric stages in order, this list will be followed. For example setting to `stage0 stage1 mystage stage2` will run the contents of `mystage` before stage2. An absolute or relative path can be given for stages outside the pi-gen directory.
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A simple example for building Raspbian:
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```bash
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IMG_NAME='Raspbian'
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```
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The config file can also be specified on the command line as an argument the `build.sh` or `build-docker.sh` scripts.
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```
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./build.sh -c myconfig
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```
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This is parsed after `config` so can be used to override values set there.
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## How the build process works
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The following process is followed to build images:
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* Loop through all of the stage directories in alphanumeric order
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* Move on to the next directory if this stage directory contains a file called
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"SKIP"
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* Run the script ```prerun.sh``` which is generally just used to copy the build
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directory between stages.
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* In each stage directory loop through each subdirectory and then run each of the
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install scripts it contains, again in alphanumeric order. These need to be named
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with a two digit padded number at the beginning.
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There are a number of different files and directories which can be used to
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control different parts of the build process:
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- **00-run.sh** - A unix shell script. Needs to be made executable for it to run.
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- **00-run-chroot.sh** - A unix shell script which will be run in the chroot
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of the image build directory. Needs to be made executable for it to run.
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- **00-debconf** - Contents of this file are passed to debconf-set-selections
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to configure things like locale, etc.
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- **00-packages** - A list of packages to install. Can have more than one, space
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separated, per line.
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- **00-packages-nr** - As 00-packages, except these will be installed using
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the ```--no-install-recommends -y``` parameters to apt-get.
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- **00-patches** - A directory containing patch files to be applied, using quilt.
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If a file named 'EDIT' is present in the directory, the build process will
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be interrupted with a bash session, allowing an opportunity to create/revise
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the patches.
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* If the stage directory contains files called "EXPORT_NOOBS" or "EXPORT_IMAGE" then
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add this stage to a list of images to generate
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* Generate the images for any stages that have specified them
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It is recommended to examine build.sh for finer details.
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## Docker Build
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Docker can be used to perform the build inside a container. This partially isolates
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the build from the host system, and allows using the script on non-debian based
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systems (e.g. Fedora Linux). The isolate is not complete due to the need to use
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some kernel level services for arm emulation (binfmt) and loop devices (losetup).
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To build:
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```bash
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vi config # Edit your config file. See above.
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./build-docker.sh
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```
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If everything goes well, your finished image will be in the `deploy/` folder.
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You can then remove the build container with `docker rm -v pigen_work`
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If something breaks along the line, you can edit the corresponding scripts, and
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continue:
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```bash
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CONTINUE=1 ./build-docker.sh
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```
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To examine the container after a failure you can enter a shell within it using:
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```bash
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sudo docker run -it --privileged --volumes-from=pigen_work pi-gen /bin/bash
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```
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After successful build, the build container is by default removed. This may be undesired when making incremental changes to a customized build. To prevent the build script from remove the container add
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```bash
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PRESERVE_CONTAINER=1 ./build-docker.sh
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```
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There is a possibility that even when running from a docker container, the
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installation of `qemu-user-static` will silently fail when building the image
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because `binfmt-support` _must be enabled on the underlying kernel_. An easy
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fix is to ensure `binfmt-support` is installed on the host machine before
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starting the `./build-docker.sh` script (or using your own docker build
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solution).
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## Stage Anatomy
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### Raspbian Stage Overview
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The build of Raspbian is divided up into several stages for logical clarity
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and modularity. This causes some initial complexity, but it simplifies
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maintenance and allows for more easy customization.
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- **Stage 0** - bootstrap. The primary purpose of this stage is to create a
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usable filesystem. This is accomplished largely through the use of
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`debootstrap`, which creates a minimal filesystem suitable for use as a
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base.tgz on Debian systems. This stage also configures apt settings and
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installs `raspberrypi-bootloader` which is missed by debootstrap. The
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minimal core is installed but not configured, and the system will not quite
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boot yet.
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- **Stage 1** - truly minimal system. This stage makes the system bootable by
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installing system files like `/etc/fstab`, configures the bootloader, makes
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the network operable, and installs packages like raspi-config. At this
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stage the system should boot to a local console from which you have the
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means to perform basic tasks needed to configure and install the system.
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This is as minimal as a system can possibly get, and its arguably not
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really usable yet in a traditional sense yet. Still, if you want minimal,
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this is minimal and the rest you could reasonably do yourself as sysadmin.
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- **Stage 2** - lite system. This stage produces the Raspbian-Lite image. It
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installs some optimized memory functions, sets timezone and charmap
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defaults, installs fake-hwclock and ntp, wifi and bluetooth support,
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dphys-swapfile, and other basics for managing the hardware. It also
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creates necessary groups and gives the pi user access to sudo and the
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standard console hardware permission groups.
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There are a few tools that may not make a whole lot of sense here for
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development purposes on a minimal system such as basic Python and Lua
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packages as well as the `build-essential` package. They are lumped right
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in with more essential packages presently, though they need not be with
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pi-gen. These are understandable for Raspbian's target audience, but if
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you were looking for something between truly minimal and Raspbian-Lite,
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here's where you start trimming.
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- **Stage 3** - desktop system. Here's where you get the full desktop system
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with X11 and LXDE, web browsers, git for development, Raspbian custom UI
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enhancements, etc. This is a base desktop system, with some development
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tools installed.
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- **Stage 4** - Raspbian system meant to fit on a 4GB card. More development
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tools, an email client, learning tools like Scratch, specialized packages
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like sonic-pi, system documentation, office productivity, etc. This is the
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stage that installs all of the things that make Raspbian friendly to new
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users.
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- **Stage 5** - The official Raspbian Desktop image. Right now only adds
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Mathematica.
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### Stage specification
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If you wish to build up to a specified stage (such as building up to stage 2
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for a lite system), place an empty file named `SKIP` in each of the `./stage`
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directories you wish not to include.
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Then add an empty file named `SKIP_IMAGES` to `./stage4` (if building up to stage 2) or
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to `./stage2` (if building a minimal system).
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```bash
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# Example for building a lite system
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echo "IMG_NAME='Raspbian'" > config
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touch ./stage3/SKIP ./stage4/SKIP ./stage5/SKIP
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touch ./stage4/SKIP_IMAGES ./stage5/SKIP_IMAGES
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sudo ./build.sh # or ./build-docker.sh
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```
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If you wish to build further configurations upon (for example) the lite
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system, you can also delete the contents of `./stage3` and `./stage4` and
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replace with your own contents in the same format.
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## Skipping stages to speed up development
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If you're working on a specific stage the recommended development process is as
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follows:
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* Add a file called SKIP_IMAGES into the directories containing EXPORT_* files
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(currently stage2, stage4 and stage5)
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* Add SKIP files to the stages you don't want to build. For example, if you're
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basing your image on the lite image you would add these to stages 3, 4 and 5.
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* Run build.sh to build all stages
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* Add SKIP files to the earlier successfully built stages
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* Modify the last stage
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* Rebuild just the last stage using ```sudo CLEAN=1 ./build.sh```
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* Once you're happy with the image you can remove the SKIP_IMAGES files and
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export your image to test
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# Troubleshooting
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## `binfmt_misc`
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Linux is able execute binaries from other architectures, meaning that it should be
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possible to make use of `pi-gen` on an x86_64 system, even though it will be running
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ARM binaries. This requires support from the [`binfmt_misc`](https://en.wikipedia.org/wiki/Binfmt_misc)
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kernel module.
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You may see the following error:
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```
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update-binfmts: warning: Couldn't load the binfmt_misc module.
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```
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To resolve this, ensure that the following files are available (install them if necessary):
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```
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/lib/modules/$(uname -r)/kernel/fs/binfmt_misc.ko
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/usr/bin/qemu-arm-static
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```
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You may also need to load the module by hand - run `modprobe binfmt_misc`.
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