

                      ===========================
                      Sculpt for The Curious (TC)
                      ===========================


                               Norman Feske



Introduction
############

Sculpt is a component-based desktop operating system that puts the user in
the position of full control. It is empowered by the Genode OS Framework,
which provides a comprehensive set of building blocks, out of which custom
system scenarios can be created. The name Sculpt hints at the underlying
idea of crafting, molding, and tweaking the system interactively. Starting
from a fairly minimalistic and generic base system, this tour through the
Sculpt system will cover the following topics:

* A boot image that is a live system, rescue system, and bootstrap system
  all in one,
* Ways to tweak and introspect the system,
* Formatting a hard disk or USB stick and storing files on the file system,
* Connecting to a wired or wireless network,
* Installing and deploying software, and
* Running a guest operating system inside a virtual machine.


Feedback and contact
--------------------

Your feedback is appreciated!

:Join the Genode mailing list for discussion:

  [https://genode.org/community/mailing-lists]

:Get in touch with the developers at GitHub:

  [https://github.com/genodelabs/genode]

:Contact Genode Labs for commercial inquiries:

  [https://www.genode-labs.com]

A printable PDF version of this document is available at
[https://genode.org/documentation/sculpt-tc.pdf].


Prerequisites
#############

Sculpt for The Curious (TC) is the second of four revisions planned for 2018
with a successively increased ease of use. In constrast to the initial version,
it introduces a graphical user interface for performing fundamental tasks like
connecting to a wireless network.

Sculpt TC expects that you already know your way around Genode's source tree
and tool chain. Should this not be the case, please consider the "Getting
started" section of the Genode Foundations book that is available as a free
download at [https://genode.org].


Vim skills required
===================

Sculpt TC leverages (a subset of) GNU coreutils, bash, and Vim as the user
interface for sculpting the system. If you are not yet familiar with using
Vim, you may take Sculpt TC as a welcome chance to get your toes wet. To
enjoy the experience, you should be comfortable with the following
operations:

* Opening and navigating within a text file (moving the cursor,
  using '/' to search),
* Using the insert mode to make modifications,
* Reverting accidental modifications ('u' undo),
* Saving a modified file (':w'),
* Opening a file in a secondary buffer (':e'),
* Switching between buffers (':bn' for next, ':bp' for previous),
* Copy and paste ('v' start selection, 'V' start line selection,
  'y' remember selection, 'p' paste remembered selection),
* Exiting Vim (':x' save and exit, ':q!' discard changes).


Hardware requirements and preparations
======================================

Sculpt TC should be compatible with recent Intel-based PC hardware
featuring Intel graphics, E1000 networking, Intel wireless, and AHCI.

It is tested best on laptops of the Lenovo X and T series (X220, X250,
X260, T430, T460). For experimenting with Sculpt, we recommend getting a
refurbished version of one of these. You may also find the unofficial
hardware compatibility list [http://usr.sysret.de/jws/genode/hcl.html]
helpful for finding Genode-compatible hardware.

Sculpt has been tested with screen resolutions up to 2560 x 1440. Displays
with a higher resolution are not expected to work. The sweet spot is a full-HD
display.

Please revisit the BIOS settings of your machine in the following respects:

:VT-d enabled: Even though Sculpt is able to run without an IOMMU, we
  advise to enable this option for the sandboxing of device drivers.

:VT-x enabled: Hardware-assisted virtualization is needed to run VirtualBox
  on top of Sculpt.

:Boot from USB enabled: Sculpt is usually booted from a USB stick.

:UEFI boot enabled: Sculpt TC boots via UEFI by default. The boot image
  is specially prepared such that it can be started via legacy boot on older
  machines. However, booting it via legacy boot on a modern machine is
  hit or miss.

:UEFI secure boot disabled: The Sculpt TC boot image is not cryptographically
  signed.

:Optimize for performance when battery powered: If the latter is not set,
  the hardware may behave erratically (e.g., non-working trackpoint when on
  battery).


Building the boot image
#######################

The following steps assume that you have the Genode tool chain installed on a
GNU/Linux system. For reference, Ubuntu 16.04 is known to work well.

# Clone Genode's Git repository:

  ! git clone https://github.com/genodelabs/genode.git
  ! cd genode
  ! git checkout 18.05

# Download the support for the NOVA microkernel

  ! ./tool/depot/download genodelabs/bin/x86_64/base-nova/2018-05-30

  The content is downloaded to the _public/_ directory and extracted to
  the _depot/_ directory.

# Download all ingredients for the Sculpt boot image

  ! ./tool/depot/download genodelabs/pkg/x86_64/sculpt/2018-05-31

# Create a build directory

  ! ./tool/create_builddir x86_64

# Configure the build directory by editing _build/x86_64/etc/build.conf_.
  Most importantly, enable the 'gems' source-code repository where the
  Sculpt scenario resides. In addition, the 'ports', 'dde_linux' and 'dde_ipxe'
  repository are needed as well. Second, change the default configuration
  of the 'QEMU_RUN_OPT' variable to 'image/disk' instead of 'image/iso'.
  This way, the build process will produce a valid disk image with a GPT
  partition table instead of a legacy ISO image.

# Create the Sculpt boot image (defined by the run script at
  _repos/gems/run/sculpt.run_)

  ! make -C build/x86_64 run/sculpt KERNEL=nova

  The boot image is created at _build/x86_64/var/run/sculpt.img_.

# Write the boot image to a USB stick:

  ! sudo dd if=build/x86_64/var/run/sculpt.img of=/dev/sdx bs=1M conv=fsync

  Here, '/dev/sdx' refers to the device node of your USB stick. To determine
  it, you may inspect the output of 'dmesg' after plugging it in.


Base system
###########

Unless customized, the Sculpt base system resides as a self-contained live
operating system on a USB stick, not installed on disk. This has two
advantages. First, it makes the update of the base system straight-forward
and completely risk-free. Simply install the new version on a second USB
stick. Should the new version cause any trouble, one can fall back to the
original one by swapping the USB sticks. Second, it alleviates the need to
install any boot-loader infrastructure on disk. In fact, we will not create
a partition table and use the entire disk as one file system.

_Note that Genode is not limited to booting from USB. It also supports_
_the use of partitions. But for this guide, we keep things as simple as_
_possible._


System overview
===============

;        Drivers    |    Leitzentrale    |    Runtime
;       subsystem   |     subsystem      |   subsystem
;    ---------------+--------------------+---------------
;                  static part of the system
;    ----------------------------------------------------
;                     microkernel / core

[image sculpt_overview]
  System overview

The Sculpt system consists of four parts living on top of the microkernel
(Figure [sculpt_overview]).


Static system
-------------

The first - static - part of the system is baked into the boot image. It
contains components that must be shared by the upper - dynamic - parts and
defines the relationships between the upper parts via a static policy that
is fixed by the creator of the boot image.

;         Drivers      |   Leitzentrale   |     Runtime
;    --------------------------------------------------------
;                            :     :
;       Nitpicker    Report  :     :  ROM    [global policy]
;      GUI server         :  :     :  :
;                         v  v     v  v
;                        Report   Config
;                          FS       FS

[image sculpt_static]
  Detailed look at the static part of the system

Besides a low-complexity GUI multiplexer called Nitpicker, the static
system contains two in-memory file systems. The _config_ file system stores
configuration data whereas the _report_ file system stores information
reported by components. These file systems are invisible to regular
components. Components obtain their configuration data from a (read-only
memory) ROM service, and report their state to a (write-only) report
service.

At boot time, the config file system is pre-populated with information from
the boot image. It stays in memory. Hence, after rebooting the system, any
changes are gone.


Drivers subsystem
-----------------

The drivers subsystem provides all the basic services needed to realize an
interactive system scenario: a framebuffer service for the graphical
output, an input service to obtain user input, and a block service to
access a storage device. All other drivers like networking or audio drivers
are not covered by the drivers subsystem. They will enter the picture at a
later stage and will use the platform service and USB service to access
device resources.

;                                        Framebuffer     AHCI
;                                          Driver       Driver
;                                             :  \     /  :
;   ACPI --- Platform ------- USB      Driver :  Dynamic  :
; discover    driver -- PS/2 :   :    Manager :    Init   :
;               :        :   :   :            :           :
;               :        :   :   :            :           :
;               :        Input   :            :           :
;               :       Filter   :            :           :
;               :          :     :            :           :
;               :          :     :            :           :
;          (platform)  (input) (USB)    (framebuffer)  (block)

[image sculpt_drivers 80%]
  Services provided by the drivers subsystem

As illustrated by Figure [sculpt_drivers], some drivers like the framebuffer
driver live in a dynamically managed subsystem that depends on runtime
discovery of the hardware by the so-called driver-manager component.
Whenever an Intel graphics device is present, the Intel framebuffer driver
is spawned. Otherwise, a generic VESA driver or a driver for a
boot-time-initialized framebuffer is used.

Several components of the drivers subsystem report their state. E.g., when
the Intel framebuffer is used, it reports the list of connectors present.
Most importantly, the driver manager reports the available block devices.

As user input may enter the system in multiple ways - most prominently PS/2
and USB HID - the drivers subsystem contains a so-called input-filter
component that merges these event streams and applies transformations like
key remappings or mouse acceleration.


Leitzentrale subsystem
----------------------

The Leitzentrale gives you - the user - full control over the config file
system and the report file system. You are free to inspect and
manipulate the system in any way you wish. The German term Leitzentrale
refers to a control center that requires a certain degree of sophistication
from the operator, which would be you. A typo at the wrong place may
render your system temporarily inaccessible, eventually requiring a reboot.
But don't be afraid. Since all manual changes performed in the Leitzentrale
occur in memory only, you are not at risk of permanently bricking your machine.

The Leitzentrale can be toggled at any time by pressing F12 and will be enabled
right after boot. It presents itself with a minimalistic GUI for accessing
the storage devices attached to your machine and for configuring your network
connectivity. Most importantly, however, it allows the user to spawn an
interactive shell for manual _config_ and _report_ file
systems access. To spawn this command-line interface, click on the "ram" item from
the menu and select "Inspect".

[image noux 45%]
  Noux runtime environment for executing Unix tools

The inspect window hosts a small Unix runtime called noux (Figure [noux])
as user interface. Don't let the presence of a Unix shell mislead you.
Sculpt is not a Unix system. It merely uses Unix subsystems in the form of
noux instances as convenient tools for managing and editing files.
Within the inspect window, you can interact with both the report and
config file systems using familiar commands such as the bash shell, a
subset of coreutils, and Vim.

Besides the interactive shell, the Leitzentrale employs a noux instance that
gives you a quick glance at the most recent log messages. The log is also
available at _report/log_ and can be browsed with Vim in the inspect window.

_Noux is not bullet-proof. Should you get stuck, you may re-spawn it at_
_any time by toggling the "Inspect" button._


Tweaking and inspecting the system
==================================

The Leitzentrale subsystem empowers you to interactively inspect and tweak
the running system. Let's take a walk next.


Adjusting the user-input handling
---------------------------------

By default, Sculpt uses the US-English keyboard layout with a functioning
capslock key. You may possibly want to adjust the former and - as a Vim
user - most likely discharge the latter. As mentioned in Section
[Drivers subsystem], user input is processed by the input-filter component.
You can edit this component's configuration via

! inspect:/> vim /config/input_filter

To change the keyboard layout to German, change "en_us.chargen" to
"de.chargen" and save the file. The change becomes effective immediately at
saving time.

To remap the capslock key to escape - a key often needed while using Vim -
uncomment the corresponding '<remap>' rule

! <key name="KEY_CAPSLOCK" to="KEY_ESC"/>

After saving the file, a Vim user's life suddenly becomes much more
pleasant.

[image input_filter 80%]
  Filter chain for user-input events

Take the time to review the remaining parts of the input-filter
configuration. The nested configuration nodes define a hierarchy of
filters that are applied in the order from the inside to outside
(Figure [input_filter]). There are filters for merging events ('<merge>'),
remapping buttons and keys ('<remap>'), supplementing symbolic character
information ('<chargen>'), pointer acceleration ('<accelerate>'), and
emulating a scroll wheel by moving the pointer while pressing the middle
mouse button ('<button-scroll>').


Display settings
----------------

If you are running the Intel graphics driver, you can inspect the connected
displays and their supported resolutions by taking a look at the report at
_/report/drivers/dynamic/intel_fb_drv/connectors_. This report is updated
whenever a display is connected or disconnected. You can use this
information to enable or disable a display in the driver's configuration,
which you can find at _/config/fb_drv_. Please don't forget to
correctly specify all attributes including the 'hz' attribute. Otherwise,
the driver will not consider the '<connector>' setting.

For a quick test, change the attribute 'height="768"' to 'force_height="768"'
(you may modify 'width' analogously). When saving the file, the screen
real-estate will forcibly be limited to the specified size. This is helpful
during presentations where the projector has a lower resolution than the
laptop's internal display. By specifying the beamer's resolution, both the
laptop and the beamer show the same content.


Exploring the drivers and Leitzentrale subsystems
-------------------------------------------------

You can review the construction plan of the drivers subsystem by opening the
file _/config/drivers_ in Vim. In particular, it is interesting to
follow the '<route>' rules to see how the various components are connected.
But there is more. The configuration is live. It enables you to reconfigure
individual components on-the-fly. For example, search for the '<start>' node
of the PS/2 driver and add the attribute 'verbose_keyboard="yes"' to the
embedded '<config>' node. By saving the file, the changed configuration
becomes effective. Any key pressed or released on the PS/2 keyboard will
result in a log message on the right. You may revert this change (vim: 'u')
and save the original version of the file.

_Note that not all components are dynamically reconfigurable but many_
_modern ones - in particular the init component and most long-running_
_server components - are._

_It is possible to forcibly restart a component by adding a 'version'_
_attribute to the '<start>' node. Whenever the 'version' value is changed,_
_the component is re-spawned._

_The component-specific configuration options are documented in the README_
_files accompanying the respective components in the source tree._

Analogously to the drivers subsystem, you can find the construction plan
for the Leitzentrale subsystem at _/config/leitzentrale_. Try out
the following tweaks:

* Change the transparency of the two noux instances by modifying the
  'alpha' attribute of the 'fader' component.

* Change the font size of the 'log_terminal' component from "10"
  to "18".

You may also enjoy tinkering with the configuration of the nitpicker GUI
server, which is located at _/config/nitpicker_. For example, you
may change the background color or the labeling color of the "default"
domain.


Runtime management
##################

[image sculpt_runtime_highlighted]

So far, we have not lost any words on the third subsystem called
"runtime" that exists besides the drivers and Leitzentrale subsystems.
The runtime subsystem has no predefined purpose but can be filled with
life at your wish.

Analogously to the drivers subsystem, the current configuration of the runtime
subsystem is located at _/config/runtime_. Where the initial Sculpt EA
version required the user to control the runtime configuration manually,
Sculpt TC automates these steps through the interactive Sculpt manager that is
hosted in the Leitzentrale subsystem. You can click on any of those items to
reveal possible operations of the selected item.

For the start, it is best to experiment with the "ram" in-memory file system.
In the previous section, we have already launched the inspect window via the
"Inspect" button of the in-memory file system. By additionally selecting the
"Use" button, we tell the Sculpt manager that we intent to use this file
system as storage location for the Sculpt session. This has two immediate
effects. First, any files present at _config/<version>/_ at the selected file
system are copied to the config file system. As the RAM file system is empty,
no files are copied. Second, the so-called _depot/_ is initialized at the
selected file system. The depot is the designated place for the installation
of software packages. By default, the depot is initialized such that the
Sculpt system accepts software published by Genode's core developers. You may
inspect the content of _/ram/depot_ using the inspect window.

The second dialog of the menu presents options for network connectivity.
In order to install any software packages, one needs to select either
"Wired" or "Wifi". In the latter case, one is prompted with the selection
of an access point and the WPA passphrase (if needed). Once connected, the
network dialog displays the IP address of the machine.

With a file system selected and an Internet connection, it is time to
install and run additional software. The interface for software installation
and deployment is the _/config/deploy_ file. It contains a number of
commented-out template snippets for various subsystems. As a first test,
uncomment the '<start>' entries for the _fonts_fs_, _wm_, and _backdrop_.
When saving the file, the Sculpt manager will automatically kick off the
download of the selected packages and its dependencies and thereby
populate the depot. Once the download has completed, the packages are
started. Pay special attention to the '<route>' definitions. They define
how the respective subsystem is connected to other parts of the system.
For example, by default, the backdrop is directly connected to the nitpicker
GUI server of the base system (parent). By changing the route from '<parent/>'
to '<child name="wm"/>' the backdrop subsystem will be connected to the window
manager instead.


Storage device access and preparation
=====================================

Whereas the RAM file system is practical for quick tests, it goes without
saying that we want to persistently store data, programs, and configuration
information on a storage device. Sculpt TC supports SATA disks, NVMe devices,
and USB-storage devices. The storage dialog lists all devices detected by
the drivers subsystem. A click on a device reveals possible operations or -
if a partition table is present - more details about the device structure.

Depending on the operation selected by the user, the Sculpt manager will
automatically reshape the runtime subsystem to perform the selected operation.
For example, by selecting the "Format device" operation, the Sculpt manager
will create a noux instance with the selected block device mounted at
'/dev/block' and e2fsprogs mounted at '/'. The noux instance runs
'mkfs.ext2' as init process. Likewise, an existing EXT2 file system
can be checked by activating the "Check" button, which triggers the execution
of 'fsck.ext2' for the selected file system.

A particularly interesting option is presented at the last partition of the
Sculpt USB stick. Initially - right after copying Sculpt's tiny disk image to
the USB stick - the partition is only a few MiB in size. However, using the
"Expand" operation, the partition can be extended to the full size of the USB
stick, which makes enough room to use the USB stick as Sculpt file system.
This clears the way for sculpting a custom live system stored entirely on
the USB stick.

All file systems supported by Sculpt present an "Inspect" button. By toggling
this button, the selected file system becomes accessible in the inspect
window. Note that more than one file system can be inspected at a time.
Each file system will appear as a directory at the root of the inspect
directory tree, named after the corresponding device and partition number.
This way, the inspect window becomes a convenient tool for copying files
between file systems. Under the hood, the Sculpt manager spawns a file-system
component for each inspected file system, which translates the notion of files
and directories to block-device accesses.


Making customizations permanent
===============================

It is possible to make any customization of the config file system
permanent by copying the modified files to a directory named
'config/<version>' on a persistent file system where '<version>' corresponds
to the Sculpt version number as found in the '/VERSION' file.
Each time, this file system is selected for "Use", those files will be
automatically copied to the in-memory config file system. Note that this
mechanism works even for the '/config/deploy' file, which allows one to
restore a once sculpted system composition directly at boot time.

To streamline the boot procedure into a customized Sculpt system even more,
it is possible to mark one file system as default. At boot time - when the
Sculpt manager discovers the attached storage devices - it automatically
selects a file system for use according to the following order of preference:

# Partition labeled as "GENODE*" on a USB device,
# Partition labeled as "GENODE*" on a SATA or NVMe storage device,
# An entire SATA or NVMe device used as a single EXT2 file system (as devised
  by Sculpt EA).

The storage dialog hosts a convenient "Default" button that allows one
to toggle a partition label between "GENODE" and "GENODE*". For example,
the last partition of the Sculpt USB stick can be marked as default or
non-default using this button.


Examples
########

The _config/deploy_ file contains several example subsystems that are
installed on demand when uncommenting the corresponding '<start>' nodes.

:'fonts_fs': A file-system server that transforms TrueType fonts into
  glyph images, which become thereby accessible as virtual files.
  This provides a hook for customizing the font size of any component that
  uses the font server, and relieves components from depending on a specific
  font-rendering library. According to the '<route>' information, its
  configuration is taken from _/config/managed/fonts_. The 'fonts_fs'
  is used by the graphical terminal of the noux subsystem and the 'top_view'
  application.

:'wm': A window manager that displays clients in windows that can be arranged
  with the mouse.

:'backdrop': A wallpaper that adjusts itself to any screen size.

:'nano3d': A simple software-rendering demo, which can be adjusted at runtime
  by modifying its configuration. E.g., by adding a custom config node
  directly inside the '<start>' node, the appearance can be changed on the fly:
  ! <config painter="shaded" shape="cube"/>

:'noux': A noux instance with a graphical terminal, similar to the
  inspect window of the leitzentrale. Note the routing of the various
  file-system sessions.

:'shared_fs': A file-system server that provides the _/shared_ sub directory
  of the Sculpt file system as a new file system. A client of this server
  won't see any other parts of the file system.

:'usb_devices_rom': A hook for assigning USB devices to a virtual machine,
  explained in Section [Updating the USB boot device from within VirtualBox].

:'vm_fs': A file-system server that provides the _/vm/debian/_ sub directory
  of the Sculpt file system as a new file system. It is explained in Section
  [Hosting a guest operating system].

:'top_view': An application that shows the CPU load, similar to 'top'.

:'2048': A _Threes!_ inspired puzzle game running in a native Libretro runtime.

:'vbox5-tc-browser': A throw-away virtual machine for running Firefox on
  TinyCore Linux. It uses VirtualBox as virtual-machine monitor.

:'seoul-tc-browser': The same virtual machine as 'vbox5-tc-browser' but
  executed inside the light-weight Seoul virtual-machine monitor.

:'qt5_textedit': Qt5-based text editor that is explicitly granted access to
  the config file system. You may change the route to other file-system
  services. For example, by specifying '<child name="shared_fs"/>' instead of
  '<parent label="config"/>' you can edit the shared folder of 'vm' subsystem.


Hosting a guest operating system
################################

The default deploy configuration found at _/config/deploy_ contains all the
pieces needed to host a virtual machine on top of Sculpt. A virtual machine
(VM) is a convenient stop-gap solution for running programs that are not yet
available natively on Genode. It ultimately enables us to use Sculpt as
day-to-day OS today.

By convention, we host the content of each VM in a dedicated
directory _/vm/<guest-os>/_ at the file system. The VM directory contains
a virtual disk image(s) as well as the VM configuration.
To install the ingredients for running Debian in the VM,
you may start the 'download_debian' subsystem, which will automatically
download the ISO image of the Debian installer and install a reasonable
VM configuration. The subsystem requests a file-system session
that points to the target directory. To pass the _/vm/debian_ directory
to the subsystem, the file-system session is routed to the 'vm_fs' component.
Please make sure to uncomment this component along with the 'download_debian'
subsystem.

Please review and adjust the _machine.vbox_ file as needed, in particular
you may reconsider the amount of RAM by changing the 'RAMSize' attribute.
To start the VM, remove the comments around the following snippets within
_/config/deploy_:

# "wm" - the window manager that will host a window of the VM,
# "vm_fs" - the location of the virtual-disk image and VM configuration,
# "shared_fs" - the location for sharing files between the guest OS and
  other parts of the Sculpt system,
# "usb_devices_rom" - a configuration that contains a list of USB devices
  passed to the VM,
# "vm" - the virtual machine.

After saving the file, VirtualBox should appear, starting the Debian
installer.

After the installation is finished and the guest system was rebooted, it is
time to install the guest additions of VirtualBox. To do that, the apt(1)
configuration has to be adjusted. Edit the file

! # vi /etc/apt/sources.list

and add the line

! deb http://ftp.debian.org/debian stretch-backports main contrib non-free

Afterwards update the package cache

! # apt update

and upgrade the packages

! # apt upgrade

and install the Linux kernel headers

! # apt install linux-headers-amd64

Just to be sure that the guest additions will use the newest kernel, reboot
the guest system. Next, install all needed packages for the guest
additions:

! # apt install virtualbox-guest-dkms virtualbox-guest-x11

Having the Linux-header package is mandatory as the needed modules will not
be built without it. After the packages are installed and the modules have
been built, certain features like the dynamic mode-setting and shared
folders can be used.

The example _machine.vbox_ file already provides a configured shared folder
called 'shared'. By executing

! # mount -t vboxsf shared /mnt/

it can be mounted and accessed via '/mnt'.


Advanced usage
##############

Manual configuration
====================

Thanks to the Sculpt manager component of the Leitzentrale, many typical
work flows and configuration tweaks are largely automated. For example,

* The management of storage devices,
* The creation of file-system components for used or inspected file systems,
* The selection and configuration of network access,
* Font size selection depending on the screen resolution,
* Triggering the download of missing depot content on demand.

This convenience comes at the price of built-in policy, which may stand in
the way of sophisticated scenarios. For this reason, almost all policies
of the Sculpt manager can be manually overriden by manually managing
configuration files.

The Sculpt manager interacts with the rest of the system solely by
monitoring reports aggregated in the report file system, and writing
configuration files into the config file systems. All files generated
by the Sculpt manager are located at _/config/managed/_. By manually creating a
same-named file at _/config/_, one can supply a custom managed configuration
to the Sculpt manager. A useful practice is taking a snapshot of the
generated configuration as a starting point for the custom version. For
example, by copying the NIC router configuration while it is connected to
a network:

! cp /config/managed/nic_router /config

Now, the copy at _/config/nic_router_ can be edited. Note that changes
usually take immediate effect.

Examples of manual customization are:
* Adding custom NIC router policies such as port-forwarding rules,
* Installing depot content manually by managing _/config/installation_
  by hand. This includes the ability to download the source code for
  any package.
* Disarming the automated update mechanism by using a _/config/installation_
  file with no '<archive>' entries.
* Fixing the current state of the runtime subsystem by copying
  _/config/managed/runtime_ to _/config/runtime_. This allows one to
  manually tweak and inspect the runtime in any way, e.g., to enable
  additional reporting when troubleshooting.
* Manually defining the default font sizes by creating a custom _config/fonts_
  configuration.
* Managing Wifi credentials manually by supplying a custom _config/wlan_ file.

To revert any manual customization, delete the corresponding file. In this
case, the Sculpt manager will take over again. Note that all manual
customizations can be made permanent by following the steps explained in
Section [Making customizations permanent].


Reproducing the system from source
==================================

Section [Building the boot image] presents the creation of the boot image
from pre-built packages. You may want to build those packages from source,
in particular for customizing the system.

Before building the packages, various ports of 3rd-party software need to
be prepared. The following command prepares all of them at once:

! <genode-dir>/tool/ports/prepare_port \
!      bash coreutils curl dde_ipxe dde_linux \
!      dde_rump e2fsprogs gnupg grub2 jitterentropy \
!      libarchive libc libgcrypt libiconv libssh \
!      lwip_legacy ncurses nova openssl qemu-usb \
!      stdcxx vim virtualbox5 x86emu xz zlib libpng \
!      ttf-bitstream-vera stb

The ingredients of the boot image are subsumed by the 'pkg/sculpt' package.
The default set of software installed by the update runtime is defined by
the 'pkg/sculpt-installation' package. You can find the depot recipes for
these packages at _repos/gems/recipes/pkg/_.

The _repos/gems/run/sculpt.run_ script can be executed to build a boot image.
By default, the boot image refers to 'genodelabs/pkg/sculpt' and to
'genodelabs/pkg/sculpt-installation' for the runtime-installed software. You
may want to install your version of these packages instead by changing the
package provider from 'genodelabs' to '<you>' by adding the line

! RUN_OPT += --depot-user <you>

to your _<build-dir>/etc/build.conf_.

To build the packages for the boot image:

! <genode-dir>/tool/depot/create \
!      UPDATE_VERSIONS=1 FORCE=1 REBUILD= \
!      <you>/pkg/x86_64/sculpt \
!      <you>/bin/x86_64/base-nova

The 'FORCE=1' argument ensures that source archives are re-created and
checked for the consistency with their versions. If the source code of any
of the archives changed, the 'UPDATE_VERSIONS=1' argument automatically
updates its version. Please don't forget to commit the updated 'hash'
files. The empty 'REBUILD=' argument limits the creation of binary packages
to those that do not yet exist in binary form. If not specified, the
command would recompile all packages each time. You may further add '-j<N>'
to parallelize the build process where '<N>' is the level of parallelism.

Building the 'sculpt-installation' package works analogously to the 'sculpt'
package.

! <genode-dir>/tool/depot/create \
!      UPDATE_VERSIONS=1 FORCE=1 REBUILD= \
!      <you>/pkg/x86_64/sculpt-installation

To make the 'sculpt-installation' available for download from within the
boot image, you must publish it. This involves the archiving, signing,
and uploading of the content. The former two steps are covered by the
_tool/depot/publish_ tool, which expects one to specify a concrete version.
The current version of the 'sculpt-installation' can be obtained via

! cat <genode-dir>/repos/gems/recipes/pkg/sculpt-installation/hash

The first part is the version. The second part is the content hash of the
version. For more information about working with the depot tool, refer to
[http://genode.org/documentation/developer-resources/package_management].


Updating the USB boot device from within VirtualBox
===================================================

The _/config/deploy_ example is prepared to assign USB storage
devices directly to a running virtual machine. You may inspect the report
_/report/drivers/usb_active_config_ to get a list of attached USB devices.
Use Vim to copy the '<policy>' node of the selected device into the
'<inline>' section of the 'usb_devices_rom' start node within your
_/config/deploy/config_, and adjust the line as follows:

* Replace the node type '<policy>' by '<device>', and
* Rename the attribute 'label_suffix' to 'label'.

The updated 'usb_devices' ROM prompts VirtualBox to open a USB session at
the drivers subsystem. Hence, when saving the modified
_/config/deploy_ file, the guest OS should detect a new USB device
(check the output of 'dmesg'). You may now write a new version of the
Sculpt ISO image to the device by following the steps described in Section
[Building the boot image].


Credits
#######

Sculpt is an example system scenario of the Genode project, which is an
operating-system technology designed and developed from scratch.

:Genode OS Framework:
  [https://genode.org]

That said, Genode is not developed in a vacuum. It rather stands on the
shoulders of giants and greatly benefits from the free-software/open-source
community. The following projects play a particularly important role for
the Sculpt scenario.

:NOVA microhypervisor:

  Sculpt's kernel is a derivate of NOVA, maintained by Genode Labs.
  NOVA was originally created by Udo Steinberg [http://hypervisor.org].

:Linux kernel:
  [https://kernel.org]

  Sculpt reuses several Linux subsystems as individual components, in
  particular the USB stack, the Intel wireless stack, the Intel graphics
  driver, and the TCP/IP stack.

:NetBSD's rump kernel:
  [https://wiki.netbsd.org/rumpkernel/]

  The file-system support is based on NetBSD kernel code, which became
  reusable on Genode thanks to the rump kernel project.

:FreeBSD:
  [https://www.freebsd.org/]

  The C runtime that is used by most 3rd-part software is based on FreeBSD's
  libc.


Device drivers
--------------

:WPA supplicant:
  [https://w1.fi/wpa_supplicant/]
  _(used by the wireless driver)_

:iPXE:
  [http://ipxe.org]
  _(basis of the wired network driver)_

:xf86emu:
  [http://xorg.freedesktop.org/]
  _(used by the VESA driver)_


Programs and libraries used within the noux runtime
---------------------------------------------------

:Vim:
  [http://www.vim.org]

:ncurses:
  [https://www.gnu.org/software/ncurses/ncurses.html]

:GNU coreutils:
  [https://www.gnu.org/software/coreutils/coreutils.html]

:GNU bash:
  [https://www.gnu.org/software/bash/]

:E2fsprogs:
  [http://e2fsprogs.sourceforge.net/]


Libraries used for the package-management infrastructure
--------------------------------------------------------

:curl:
  [https://curl.haxx.se]
  _(basis of the fetchurl tool)_

:libssh:
  [https://www.libssh.org]

:OpenSSL:
  [https://www.openssl.org]

:XZ Utils:
  [https://tukaani.org/xz/]
  _(support for tar.xz archives)_

:libarchive:
  [https://www.libarchive.org]
  _(basis of the extract tool)_

:zlib:
  [https://www.zlib.net]

:GnuPG:
  [https://www.gnupg.org]
  _(basis of the verify tool)_


Applications
------------

:VirtualBox:
  [https://www.virtualbox.org]
  _(used for hosting virtual machines)_


Crucial tools used during development
-------------------------------------

:GNU/Linux: (various distributions)

:Git:
  [https://git-scm.com]

:GNU compiler collection:
  [https://gcc.gnu.org]

:GNU binutils:
  [https://www.gnu.org/software/binutils/]

:GNU make:
  [https://www.gnu.org/software/make/]

:Tcl:
  [https://www.tcl.tk]

:Expect:
  [http://expect.sourceforge.net]

:Qemu:
  [https://www.qemu.org]

:GitHub issues:
  [https://github.com]

