Add sphinx documentation

6 files changed, 771 insertions, 0 deletions

diff --git a/doc/Makefile b/doc/Makefile
new file mode 100644
index 0000000..551fe06
--- /dev/null
+++ b/doc/Makefile
@@ -0,0 +1,153 @@
+# Makefile for Sphinx documentation
+#
+
+# You can set these variables from the command line.
+SPHINXOPTS    =
+SPHINXBUILD   = sphinx-build
+PAPER         =
+BUILDDIR      = _build
+
+# Internal variables.
+PAPEROPT_a4     = -D latex_paper_size=a4
+PAPEROPT_letter = -D latex_paper_size=letter
+ALLSPHINXOPTS   = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
+# the i18n builder cannot share the environment and doctrees with the others
+I18NSPHINXOPTS  = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
+
+.PHONY: help clean html dirhtml singlehtml pickle json htmlhelp qthelp devhelp epub latex latexpdf text man changes linkcheck doctest gettext
+
+help:
+	@echo "Please use \`make <target>' where <target> is one of"
+	@echo "  html       to make standalone HTML files"
+	@echo "  dirhtml    to make HTML files named index.html in directories"
+	@echo "  singlehtml to make a single large HTML file"
+	@echo "  pickle     to make pickle files"
+	@echo "  json       to make JSON files"
+	@echo "  htmlhelp   to make HTML files and a HTML help project"
+	@echo "  qthelp     to make HTML files and a qthelp project"
+	@echo "  devhelp    to make HTML files and a Devhelp project"
+	@echo "  epub       to make an epub"
+	@echo "  latex      to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
+	@echo "  latexpdf   to make LaTeX files and run them through pdflatex"
+	@echo "  text       to make text files"
+	@echo "  man        to make manual pages"
+	@echo "  texinfo    to make Texinfo files"
+	@echo "  info       to make Texinfo files and run them through makeinfo"
+	@echo "  gettext    to make PO message catalogs"
+	@echo "  changes    to make an overview of all changed/added/deprecated items"
+	@echo "  linkcheck  to check all external links for integrity"
+	@echo "  doctest    to run all doctests embedded in the documentation (if enabled)"
+
+clean:
+	-rm -rf $(BUILDDIR)/*
+
+html:
+	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
+	@echo
+	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
+
+dirhtml:
+	$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
+	@echo
+	@echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml."
+
+singlehtml:
+	$(SPHINXBUILD) -b singlehtml $(ALLSPHINXOPTS) $(BUILDDIR)/singlehtml
+	@echo
+	@echo "Build finished. The HTML page is in $(BUILDDIR)/singlehtml."
+
+pickle:
+	$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle
+	@echo
+	@echo "Build finished; now you can process the pickle files."
+
+json:
+	$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json
+	@echo
+	@echo "Build finished; now you can process the JSON files."
+
+htmlhelp:
+	$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
+	@echo
+	@echo "Build finished; now you can run HTML Help Workshop with the" \
+	      ".hhp project file in $(BUILDDIR)/htmlhelp."
+
+qthelp:
+	$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp
+	@echo
+	@echo "Build finished; now you can run "qcollectiongenerator" with the" \
+	      ".qhcp project file in $(BUILDDIR)/qthelp, like this:"
+	@echo "# qcollectiongenerator $(BUILDDIR)/qthelp/vmdebootstrap.qhcp"
+	@echo "To view the help file:"
+	@echo "# assistant -collectionFile $(BUILDDIR)/qthelp/vmdebootstrap.qhc"
+
+devhelp:
+	$(SPHINXBUILD) -b devhelp $(ALLSPHINXOPTS) $(BUILDDIR)/devhelp
+	@echo
+	@echo "Build finished."
+	@echo "To view the help file:"
+	@echo "# mkdir -p $$HOME/.local/share/devhelp/vmdebootstrap"
+	@echo "# ln -s $(BUILDDIR)/devhelp $$HOME/.local/share/devhelp/vmdebootstrap"
+	@echo "# devhelp"
+
+epub:
+	$(SPHINXBUILD) -b epub $(ALLSPHINXOPTS) $(BUILDDIR)/epub
+	@echo
+	@echo "Build finished. The epub file is in $(BUILDDIR)/epub."
+
+latex:
+	$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
+	@echo
+	@echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex."
+	@echo "Run \`make' in that directory to run these through (pdf)latex" \
+	      "(use \`make latexpdf' here to do that automatically)."
+
+latexpdf:
+	$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
+	@echo "Running LaTeX files through pdflatex..."
+	$(MAKE) -C $(BUILDDIR)/latex all-pdf
+	@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
+
+text:
+	$(SPHINXBUILD) -b text $(ALLSPHINXOPTS) $(BUILDDIR)/text
+	@echo
+	@echo "Build finished. The text files are in $(BUILDDIR)/text."
+
+man:
+	$(SPHINXBUILD) -b man $(ALLSPHINXOPTS) $(BUILDDIR)/man
+	@echo
+	@echo "Build finished. The manual pages are in $(BUILDDIR)/man."
+
+texinfo:
+	$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
+	@echo
+	@echo "Build finished. The Texinfo files are in $(BUILDDIR)/texinfo."
+	@echo "Run \`make' in that directory to run these through makeinfo" \
+	      "(use \`make info' here to do that automatically)."
+
+info:
+	$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
+	@echo "Running Texinfo files through makeinfo..."
+	make -C $(BUILDDIR)/texinfo info
+	@echo "makeinfo finished; the Info files are in $(BUILDDIR)/texinfo."
+
+gettext:
+	$(SPHINXBUILD) -b gettext $(I18NSPHINXOPTS) $(BUILDDIR)/locale
+	@echo
+	@echo "Build finished. The message catalogs are in $(BUILDDIR)/locale."
+
+changes:
+	$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes
+	@echo
+	@echo "The overview file is in $(BUILDDIR)/changes."
+
+linkcheck:
+	$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck
+	@echo
+	@echo "Link check complete; look for any errors in the above output " \
+	      "or in $(BUILDDIR)/linkcheck/output.txt."
+
+doctest:
+	$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
+	@echo "Testing of doctests in the sources finished, look at the " \
+	      "results in $(BUILDDIR)/doctest/output.txt."
diff --git a/doc/conf.py b/doc/conf.py
new file mode 100644
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+++ b/doc/conf.py
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+# -*- coding: utf-8 -*-
+#
+# vmdebootstrap documentation build configuration file
+#
+# This file is execfile()d with the current directory set to its containing dir.
+#
+# Note that not all possible configuration values are present in this
+# autogenerated file.
+#
+# All configuration values have a default; values that are commented out
+# serve to show the default.
+
+import sys
+import os
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+sys.path.append(os.path.abspath('..'))
+
+# -- General configuration -----------------------------------------------------
+
+# Add any Sphinx extension module names here, as strings. They can be extensions
+# coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
+extensions = [
+    'sphinx.ext.autodoc',
+    'sphinx.ext.doctest',
+    'sphinx.ext.intersphinx',
+    'sphinx.ext.todo',
+    'sphinx.ext.coverage',
+    'sphinx.ext.viewcode']
+
+# Configuration for sphinx.ext.todo
+todo_include_todos = True
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# The suffix of source filenames.
+source_suffix = '.rst'
+
+# The encoding of source files.
+# source_encoding = 'utf-8'
+
+# The master toctree document.
+master_doc = 'index'
+
+# General information about the project.
+project = u'vmdebootstrap'
+copyright = u'2015 Neil Williams'
+
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
+#
+import subprocess
+# The short X.Y version.
+version = subprocess.Popen(['python', 'setup.py', '-V'], cwd=r'..', stdout=subprocess.PIPE).stdout.read().rstrip()
+# The full version, including alpha/beta/rc tags.
+release = version
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+# language = None
+
+# There are two options for replacing |today|: either, you set today to some
+# non-false value, then it is used:
+# today = ''
+# Else, today_fmt is used as the format for a strftime call.
+# today_fmt = '%B %d, %Y'
+
+# List of documents that shouldn't be included in the build.
+# unused_docs = []
+
+# List of directories, relative to source directory, that shouldn't be searched
+# for source files.
+exclude_trees = []
+
+exclude_patterns = ['pages/reference-architecture', 'tables.rst']
+
+# The reST default role (used for this markup: `text`) to use for all documents.
+# default_role = None
+
+# If true, '()' will be appended to :func: etc. cross-reference text.
+# add_function_parentheses = True
+
+# If true, the current module name will be prepended to all description
+# unit titles (such as .. function::).
+# add_module_names = True
+
+# If true, sectionauthor and moduleauthor directives will be shown in the
+# output. They are ignored by default.
+# show_authors = False
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = 'sphinx'
+
+# A list of ignored prefixes for module index sorting.
+# modindex_common_prefix = []
+
+
+# -- Options for HTML output ---------------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  Major themes that come with
+# Sphinx are currently 'default' and 'sphinxdoc'.
+html_theme = 'default'
+
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+# html_theme_options = {}
+
+# Add any paths that contain custom themes here, relative to this directory.
+# html_theme_path = []
+
+# The name for this set of Sphinx documents.  If None, it defaults to
+# "<project> v<release> documentation".
+# html_title = None
+
+# A shorter title for the navigation bar.  Default is the same as html_title.
+# html_short_title = None
+
+# The name of an image file (relative to this directory) to place at the top
+# of the sidebar.
+# html_logo = ""
+
+# The name of an image file (within the static path) to use as favicon of the
+# docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
+# pixels large.
+# html_favicon = "favicon.ico"
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['_static']
+
+# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
+# using the given strftime format.
+# html_last_updated_fmt = '%b %d, %Y'
+
+# If true, SmartyPants will be used to convert quotes and dashes to
+# typographically correct entities.
+# html_use_smartypants = True
+
+# Custom sidebar templates, maps document names to template names.
+# html_sidebars = {}
+
+# Additional templates that should be rendered to pages, maps page names to
+# template names.
+# html_additional_pages = {}
+
+# If false, no module index is generated.
+# html_use_modindex = True
+
+# If false, no index is generated.
+# html_use_index = True
+
+# If true, the index is split into individual pages for each letter.
+# html_split_index = False
+
+# If true, links to the reST sources are added to the pages.
+html_show_sourcelink = True
+
+# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
+html_show_sphinx = True
+
+# If true, an OpenSearch description file will be output, and all pages will
+# contain a <link> tag referring to it.  The value of this option must be the
+# base URL from which the finished HTML is served.
+# html_use_opensearch = ''
+
+# If nonempty, this is the file name suffix for HTML files (e.g. ".xhtml").
+# html_file_suffix = ''
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = 'vmdebootstrapdocs'
+
+
+# -- Options for LaTeX output --------------------------------------------------
+
+# The paper size ('letter' or 'a4').
+# latex_paper_size = 'letter'
+
+# The font size ('10pt', '11pt' or '12pt').
+# latex_font_size = '10pt'
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title, author, documentclass [howto/manual]).
+latex_documents = [
+    ('index', 'vmdebootstrap.tex', u'vmdebootstrap',
+     u'Neil Williams', 'manual'),
+]
+
+# The name of an image file (relative to this directory) to place at the top of
+# the title page.
+# latex_logo = None
+
+# For "manual" documents, if this is true, then toplevel headings are parts,
+# not chapters.
+# latex_use_parts = False
+
+# Additional stuff for the LaTeX preamble.
+# latex_preamble = ''
+
+# Documents to append as an appendix to all manuals.
+# latex_appendices = []
+
+# If false, no module index is generated.
+# latex_use_modindex = True
+
+
+# Example configuration for intersphinx: refer to the Python standard library.
+intersphinx_mapping = {'http://docs.python.org/': None}
diff --git a/doc/devel.rst b/doc/devel.rst
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--- /dev/null
+++ b/doc/devel.rst
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+Developing live scripts and customisation hooks
+===============================================
+
+vmdebootstrap is available in git and in Debian. The live image
+processing requires several options which are only available in
+versions of vmdebootstrap newer than version 0.5-2 available in
+Debian Jessie. vmdebootstrap is able to run on Stretch, Jessie or
+Wheezy and able to build any suite supported by debootstrap (and
+and architecture supported by QEMU) on any of those versions of
+Debian. This leads to a large matrix of build options and hooks.
+
+Calls to vmdebootstrap are best scripted. See the README for notes
+on which options and settings are required to make a live image using
+vmdebootstrap.
+
+The 'common' library contains functions and parameters which need to
+be used in *all* images, including:
+
+cleanup
+export_env
+mount_proc
+disable_daemons
+prepare_apt_source
+remove_daemon_block
+replace_apt_source
+
+cleanup
+-------
+
+Ensure that proc is unmounted even if the customisation fails or else
+the image build itself will fail to unmount ${rootdir}.
+
+export_env
+----------
+
+Debconf needs to be set in noninteractive mode to prevent the image
+build waiting for keyboard intervention.
+
+mount_proc
+----------
+
+Many packages require /proc to be mounted inside the chroot during
+installation - cleanup must be specified as a trap if mount_proc is
+used: trap cleanup 0
+
+disable_daemons
+---------------
+
+Packages which include a daemon *must not* start those daemons inside
+the chroot as this will make the ${rootdir} appear busy and the unmount
+will fail. All scripts need to use remove_daemon_block after package
+installation is complete.
+
+prepare_apt_source
+------------------
+
+The final Debian mirror location is not useful during the build as there
+is a faster mirror available during the build. This function moves the
+specified mirror file aside and uses the nearby mirror. Always use with
+replace_apt_source.
+
+replace_apt_source
+------------------
+
+Requires prepare_apt_source to have been run first, then undoes the
+change to the apt sources and cleans up.
+
+TASK_PACKAGES
+-------------
+
+Some task packages are useful to all images, these are specified here
+and should be included in the set of packages to be installed using
+all customisation scripts.
+
+EXTRA_PACKAGES
+--------------
+
+Packages which are not part of an existing task but which are useful for
+all images and should be included in the set of packages to be installed
+using all customisation scripts.
+
+Testing
+-------
+
+Testing - unsquashfs <filename> creates a squashfs-root/ directory
+containing the original image which QEMU can now use:
+$ unsquashfs jessie.img.squash
+$ qemu-system-x86_64 -machine accel=kvm:tcg -m 4096 -smp 2 -drive file=squashfs-root/jessie.img,format=raw
+
+This needs to be done on a local system which has a usable display,
+not on pettersson itself.
+
+New architectures
+-----------------
+
+The precursor to new architecture support is vmdebootstrap support. A
+default vmdebootstrap (with no customisation hook) will need to work
+and any changes to the settings (e.g. --no-kernel --package linux-myarch-flavour)
+There is default support for some architectures in vmdebootstrap
+(e.g. armhf architectures select the armmp kernel), such support depends
+on how many users would use the same kernel compared to the number of
+possible kernel flavours for that architecture.
+
+For a Debian LIVE image, *all* packages must exist in Debian.
+
+The package list also needs a review - some packages will simply not
+exist for the specified architecture. Some architecture-specific packages
+need to be added, so each architecture has a particular customisation
+hook script. Package names frequently change between releases, so the
+package selection needs to be suite specific as well.
diff --git a/doc/index.rst b/doc/index.rst
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index 0000000..8b15fd9
--- /dev/null
+++ b/doc/index.rst
@@ -0,0 +1,9 @@
+VMDebootstrap
+#############
+
+.. toctree::
+   :maxdepth: 2
+
+   overview.rst
+   live.rst
+   devel.rst
diff --git a/doc/live.rst b/doc/live.rst
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--- /dev/null
+++ b/doc/live.rst
@@ -0,0 +1,96 @@
+Initial schemes for vmdebootstrap creation of live images
+=========================================================
+
+#. vmdebootstrap has explicit support for foreign architecture
+   bootstraps using qemu static binformat handling as well as
+   support for Debian releases from wheezy onwards.
+
+#. vmdebootstrap can support adding specific packages but a
+   simpler approach is to use the existing task-* packages and
+   only add packages manually where explicitly needed for a live
+   image, e.g. ``wpa-supplicant``
+
+#. Once a standard set of packages exist, create a metapackage
+   expressing this support - possibly as a part of the vmdebootstrap
+   packaging or as part of debian-cd.
+
+#. debian-cd runs vmdebootstrap inside a VM in a similar manner to
+   how debian-live currently operates, as both debian-live and
+   vmdebootstrap need to call debootstrap which involves making
+   device nodes and needs to run as root. This outer VM is specific
+   for the release of Debian being built. vmdebootstrap can build
+   older releases and it may be necessary to use a newer version of
+   vmdebootstrap than is present in jessie to build jessie and to
+   use that version to build wheezy.
+
+#. vmdebootstrap uses a single config file per image type and each
+   config file can have a single customisation script. The config
+   file specifies the architecture of the image and the binformat
+   handler for that architecture, so the customisation hook script
+   can be architecture-specific.
+
+#. Customisation hook scripts are shell scripts which will be passed
+   a single parameter - the directory which represents the root
+   directory of the final image. These scripts can use standard shell
+   support to include other common functions or call out to utilities
+   known to be installed in the outer VM running vmdebootstrap.
+
+#. Customisation hooks clearly need to live in a VCS - possibly within
+   the debian-cd git repo.
+
+#. Although vmdebootstrap does have architecture support, the deciding
+   factor is the availability of a working default kernel for the images
+   built for that architecture and how to configure the bootloader(s) to
+   provide the relevant dtb where needed.
+
+#. Testing vmdebootstrap images uses qemu along the lines of::
+
+    $ qemu-system-x86_64 -machine accel=kvm:tcg -m 4096 -smp 2 -drive file=test.img,format=raw
+
+#. Unlike standard vmdebootstrap example scripts, the scripts calling
+   vmdebootstrap itself do not need to use sudo as the call is made inside
+   the outer VM which already has root. Using sudo will work but will output
+   a message: sudo: unable to resolve host JESSIE-debian-live-builder
+
+#. The building of live images doesn't appear to need changes in the
+   vmdebootstrap package itself. The changes to isolinux to add the menu config,
+   splash screen and to provide access to the install menus can all be done
+   in the customisation hook.
+
+#. Remember to use ``http://cdbuilder.debian.org/debian/`` for the bootstrap
+   operations (--mirror option) and ``http://httpredir.debian.org/debian`` for
+   the mirror to be used after the image has booted (--apt-mirror option).
+
+#. Ensure that a user is created (``--user 'user/live'``) and that ``sudo`` is
+   added to the set of packages to install and the --sudo option is passed
+   to vmdebootstrap to ensure that the user is added to the sudo group. The
+   root user password should also be locked (--lock-root-password).
+
+#. Installing task packages using debootstrap **omits** ``Recommended`` packages,
+   resulting in a much smaller image which is not expected for a live image.
+   Task selection needs to be done in the customisation hook using the chroot
+   command, at which point the default apt configuration will install the
+   Recommends as well as the Depends packages. Ensure that the image size is
+   big enough.
+
+#. When installing using apt in the customisation script, ensure that the
+   debconf non-interactive settings are exported to prevent the install
+   waiting for keyboard interaction. ``DEBIAN_FRONTEND=noninteractive``
+
+#. The customisation script needs to mount proc before starting the apt install.
+
+#. Calls to apt should also not output the progress bar but the actual package
+   installation steps should be logged.
+
+#. Move the image apt sources aside and set the cdimage apt source instead.
+   Use ``http://cdbuilder.debian.org/debian/`` Then, at the end of the
+   customisation hook, remove that source and replace the original.
+
+#. ``mksquashfs`` can fail without indication of why and when it does, the image
+   file can be 4Kb or so of junk. To prevent this, avoid running
+   vmdebootstrap with the ``--squash`` option and run mksquashfs as a second step
+   **after** copying the raw image to a new file for safety / debugging.
+   Newer versions of vmdebootstrap will emit a warning and not delete
+   the original file if the squashfs output is less than 1MB. This can
+   occur if the drive runs out of space but squashfs does not report
+   an error.
diff --git a/doc/overview.rst b/doc/overview.rst
new file mode 100644
index 0000000..09356c5
--- /dev/null
+++ b/doc/overview.rst
@@ -0,0 +1,190 @@
+VMDebootstrap
+#############
+
+Purpose
+*******
+vmdebootstrap is a helper to install basic Debian system into virtual
+disk image. It wraps **debootstrap**. You need to run :file:`vmdebootstrap`
+as root. If the ``--verbose`` option is not used, no output will be
+sent to the command line. If the ``--log`` option is not used, no
+output will be sent to any log files either.
+
+To use the image, you probably want to create a virtual machine using
+your preferred virtualization technology, such as file:`kvm` or
+file:`qemu`. Configure the virtual machine to use the image you've
+created. Then start the virtual machine and log into it via its console
+to configure it. The image has an empty root password and will not have
+networking configured by default. Set the root password before you
+configure networking.
+
+Networking
+**********
+
+The ``--enable-networking`` option uses the :file:`/etc/network/interfaces.d/`
+source directory, with the default settings for ``lo`` and ``eth0``
+being added to :file:`/etc/network/interfaces.d/setup`. Other networking
+configuration can be specified using a customisation script.
+Localhost settings would be::
+
+ auto lo
+ iface lo inet loopback
+
+If ``--enable-dhcp`` is specified, these settings are also included
+into :file:`/etc/network/interfaces.d/setup`::
+
+ auto eth0
+ iface eth0 inet dhcp
+
+Bootloaders
+***********
+
+Unless the ``--no-extlinux`` or ``--grub`` options are specified, the
+image will use ``extlinux`` as a boot loader. ``bootsize`` is not
+recommended when using ``extlinux`` - use ``grub`` instead.
+
+Versions of grub2 in wheezy
+===========================
+
+Grub2 in wheezy can fail to install in the VM, at which point 
+:file:`vmdebootstrap` will fall back to ``extlinux``. It may still be
+possible to complete the installation of ``grub2`` after booting the
+VM as the problem may be related to the need to use loopback devices
+during the ``grub-install`` operation. Details of the error will appear
+in the vmdebootstrap log file, if enabled with the ``--log`` option.
+
+.. note:: **grub-legacy** is not supported.
+
+:file:`vmdebootstrap` also supports **EFI**.
+
+Use ``--use-uefi`` to use ``grub-efi`` instead of ``grub-pc``. If the
+default 5Mb is not enough space, use the ``--esp-size`` option to
+specify a different size for the EFI partition. Registered firmware is
+not supported as it would need to be done after boot. If the system you
+are creating is for more than just a VM or live image, you will likely
+need a larger ESP, up to 500Mb.
+
+UBoot
+=====
+
+UBoot needs manual configuration via the customisation hook scripts,
+typically support requires adding ``u-boot`` using ``--package`` and then
+copying or manipulating the relevant ``u-boot`` files in the customisation
+script. Examples are included for beaglebone-black.
+
+Installation images and virtual machines
+****************************************
+
+:file:`vmdebootstrap`` is aimed principally at creating virtual machines,
+not installers or prebuilt installation images. It is possible to create
+prebuilt installation images for some devices but this depends on the
+specific device. (A 'prebuilt installation image' is a single image file
+which can be written to physical media in a single operation and which
+allows the device to boot directly into a fully installed system - in
+a similar way to how a virtual machine would behave.)
+
+:file:`vmdebootstrap` assumes that all operations take place on a local
+image file, not a physical block device / removable media.
+
+:file:`vmdebootstrap` is intended to be used with tools like ``qemu`` on
+the command line to launch a new virtual machine. Not all devices have
+virtualisation support in hardware.
+
+This has implications for file:`u-boot` support in some cases. If the
+device can support reading the bootloader from a known partition, like
+the beaglebone-black, then :file:`vmdebootstrap` can provide space for
+the bootloader and the image will work as a prebuilt installation image.
+If the device expects that the bootloader exists at a specific offset
+and therefore requires that the bootloader is written as an image not
+as a binary which can be copied into an existing partition,
+:file:vmdebootstrap` is unable to include that bootloader image into
+the virtual machine image.
+
+The beagleboneblack.sh script in the examples/ directory provides a worked
+example to create a prebuilt installation image. However, the beagleboneblack
+itself does not support virtualisation in hardware, so is unable to launch
+a virtual machine. Other devices, like the Cubietruck or Wandboard need
+:file:`u-boot` at a predefined offset but can launch a virtual machine
+using ``qemu``, so the cubietruck and wandboard6q scripts in the
+examples/ directory relate to building images for virtual machines once
+the device is already installed and booted into a suitable kernel.
+
+It is possible to wrap :file:`vmdebootstrap` in such a way as to prepare
+a physical block device with a bootloader image and then deploy the
+bootstrap on top. However, this does require physical media to be
+inserted and removed each time the wrapper is executed. To do this, use
+the ``--tarball`` option instead of the ``--image`` option. Then setup
+the physical media and bootloader image manually, as required for the
+device, redefine the partitions to make space for the rootfs, create a
+filesystem on the physical media and unpack the :file:`vmdebootstrap`
+tarball onto that filesystem. Once you have working media, an image can be
+created using dd to read back from the media to an image file, allowing
+other media to be written with a single image file.
+
+Example
+*******
+
+To create an image for the stable release of Debian::
+
+ sudo vmdebootstrap --image test.img --size 1g \\
+    --log test.log --log-level debug --verbose \\
+    --mirror http://mirror.lan/debian/
+
+To run the test image, make sure it is writeable. Use the ``--owner``
+option to set mode 0644 for the specified user or use chmod manually::
+
+ sudo chmod a+w ./test.img
+
+Execute using qemu, e.g. on amd64 using qemu-system-x86_64::
+
+ qemu-system-x86_64 -drive format=raw,file=./test.img
+
+(This loads the image in a new window.) Note the use of ``-drive
+file=<img>,format=raw`` which is needed for newer versions of QEMU.
+
+There is EFI firmware available to use with QEMU when testing images built
+using the UEFI support, but this software is in Debian non-free due to patent
+concerns. If you choose to install ``ovmf`` to test UEFI builds, a
+secondary change is also needed to symlink the provided ``OVMF.fd`` to
+the file required by QEMU: ``bios-256k.bin`` and then tell QEMU about
+the location of this file with the -L option::
+
+ $ qemu-system-x86_64 -L /usr/share/ovmf/ -machine accel=kvm \\
+  -m 4096 -smp 2 -drive format=raw,file=test.img
+
+For further examples, including u-boot support for beaglebone-black,
+see ``/usr/share/vmdebootstrap/examples``
+
+Notes
+*****
+
+If you get problems with the bootstrap process, run a similar bootstrap
+call directly and chroot into the directory to investigate the failure.
+The actual debootstrap call is part of the vmdebootstrap logfile. The
+debootstrap logfile, if any, will be copied into your current working
+directory on error.
+
+:file:`debootstrap` will download all the apt archive files into the apt cache and does not
+remove them before starting the configuration of the packages. This can
+mean that debootstrap can fail due to a lack of space on the device if
+the VM size is small. vmdebootstrap cleans up the apt cache once debootstrap
+has finished but this doesn't help if the package unpack or configuration
+steps use up all of the space in the meantime. Avoid this problem by
+specifying a larger size for the image.
+
+.. note:: if you are also using a separate /boot partition in your options to 
+   :file:`vmdebootstrap` it may well be the boot partition which needs
+   to be enlarged rather than the entire image.
+
+It is advisable to change the mirror in the example scripts to a mirror
+closer to your location, particularly if you need to do repeated builds.
+Use the --apt-mirror option to specify the apt mirror to be used inside
+the image, after boot.
+
+There are two types of examples for ARM devices available with
+:file:`vmdebootstrap`: prebuilt installation images (like the beaglebone-black) and virtual
+machine images (cubietruck and wandboard). ARM devices which do not
+support hypervisor mode and which also rely on the bootloader being at
+a specific offset instead of using a normal partition will
+**not** be supportable by vmdebootstrap. Similarly, devices which support
+hypervisor will only be supported using virtual machine images, unless
+the bootloader can be executed from a normal partition.