genode/repos/gems/recipes/pkg/sculpt

                      =============================
                      Sculpt Operating System 24.04
                      =============================


                               Norman Feske



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

[image sculpt_24_04 100%]

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,
* Connecting to a wired or wireless network,
* Managing and accessing storage devices,
* Installation on disk,
* Ways to tweak and introspect the system, and
* Integrity-protected package management, system update, and rollback.


Community
---------

The best place to learn more about using and tweaking Sculpt, to follow the
work of the developers, and to get hold of announcements of new software and
features is the federated Genodians blog:

:Genodians.org community blog:

  [https://genodians.org]


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 the
[https://genode.org/documentation/sculpt-24.04.pdf - Genode website].


Hardware requirements and preparations
######################################

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

It is tested best on laptops of the Lenovo X and T series (X220, X250, X260,
T430, T460, T470, T490). For experimenting with Sculpt, we recommend getting a
refurbished version of one of these. You may also find the unofficial
[https://usr.sysret.de/jws/genode/hcl.html - hardware compatibility list]
helpful for finding Genode-compatible hardware.

Sculpt has been tested with screen resolutions up to 3840 x 2160. 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 enabling this option for the sandboxing of device drivers.

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

:Execution prevention enabled: The standard Sculpt package is provided
  for x86-64 and expects your platform to support data execution
  prevention (abbreviated DEP or NX). If this feature is disabled your
  PC will just reboot on startup.

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

:UEFI boot enabled: Sculpt 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 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).


Getting a first impression
##########################

Sculpt is best explored by first booting the prebuilt disk image downloadable
from [https://genode.org/download/sculpt].
Right after system boot, Sculpt's system-management user interface
("Leitzentrale") appears.
The panel at the top of the screen contains two centered tabs for switching
between the "Components" view and a "Files" view.
The components view displays a live graph of the software components and their
relationships. It also provides convenient access to the connected storage
devices. The "Log" button on the right side of the panel reveals diagnostic
messages, the "Network" button allows you to configure network connectivity,
and the "Settings" button on the left gives access to a few user-interface
tweaks).

[image sculpt_24_04_panel 80%]

Consider the following steps as a warm-up with Sculpt OS.

Select the in-memory file system as *default storage location* by clicking
on the "ram fs" component in the graph and pressing the "Use" button.
This way, software will be installed solely into memory without accessing any
real storage device.

[image sculpt_24_04_use_ram_fs 36%]

Enable *networking* in the "Network" dialog by selecting the "Wired" or
"Wifi" option. In the latter case, select an access point and enter the
corresponding passphrase (if needed). A successful network connection is
indicated by the IP address displayed at the bottom of the network dialog.

[image sculpt_20_08_network 50%]

With a storage location selected and established network connectivity,
it is time to give a preconfigured example sculpt scenario a *quick try*.
The system menu at the upper-left screen corner reveals a couple of presets
to play with. As a first test, let's load the nano3d preset.

[image sculpt_24_04_presets 50%]

When loading the preset, Sculpt will automatically download all the needed
ingredients into the selected RAM file system and start the components of the
demo scenario, which presents a simple spinning object that follows the mouse.
*Press F12* to toggle between the administrative user interface and the running
preset at any time.
You may give the other presets a try as well:

:empty: takes you back to the initial state.

:falkon web browser: runs a disposable Chromium-based web browser entirely
  in memory.

:goa testbed: allows developers to use Sculpt OS as a remote test target using
  the Goa SDK.

:window manager: is a suitable starting point for creating a desktop-computing
  user experience on Sculpt OS.


Composing a system from scratch
===============================

Let's discover how to sculpt a custom scenario by starting
with the *empty* preset that takes us back to the initial system state. In the
following, we will build up a custom system by integrating one component
after another.

The gateway for *installing and starting* individual components is the
unassuming '+' button of the components view. The menu consists of two tabs.
The "Options" contain a list of preconfigured components that can be added
or removed via checkboxes. For example, by enabling the "mixer", one can
empower the system to mix audio signals. As of now, we can leave all options
aside and turn our attention to the "Add" tab. As the name suggests, it allows
us to add new components. It presents a choice of software sources with
"genodelabs" being preselected along with an "Update Index" button. By
updating the index, Sculpt downloads a catalog of components offered by
the selected software provider. Once the index is downloaded, the catalog is
presented as a hierarchically structured menu.

[image sculpt_24_04_update_index 50%]

Software offered by different providers can safely be installed side by side
because Sculpt keeps downloads from different providers separated. The
default "genodelabs" provider offers components officially provided by
Genode Labs.
Think of each provider as a different individual. The providers known by
the default system image are members of Genode's core developer team.
One can add a new provider by supplying a custom URL using the "Edit" button.
Note that by merely knowing a URL but no public key, Sculpt won't be able to
verify the integrity of software obtained from such manually added providers.
However, even if neither trusting one particular software provider nor the
integrity of the download, one can still install and use the provided software
without risk as long as one does not explicitly grant the untrusted components
access to sensitive parts of the system. The judgement of trust is entirely
yours.

As a starter, let's add a desktop background.
In the "GUI ..." sub menu, a click on the first item named "sticks blue
backdrop" reveals the option to install the package.

[image sculpt_24_04_install_backdrop 45%]

A click on the "Install" button triggers the download of the package and its
dependencies. Once the download is complete, the menu presents a configuration
dialog that allows you to define the interplay of the new component with the
system. In this particular case, you have to decide for a GUI service to be
used by the backdrop.

[image sculpt_24_04_backdrop_routes 45%]

The first option "system GUI server" would grant direct access to the system's
low-level GUI server, which is normally not used by applications but by
higher-level GUI servers like a window manager. The second option would give
the component the privilege to act as a lock screen. The third option would
connect the component to the special "desktop background" GUI session, which
appears as a layer behind all other applications. The fourth option "keyboard
focus" is preserved for a single component that controls the keyboard focus.
In our case, "desktop background" is the correct choice.
Once the configuration is complete, a new button for adding the component to
the system appears.

[image sculpt_24_04_add_backdrop 42%]

After pressing the button, you should notice a slight visual change. *Press*
*F12* to toggle between the Leitzentrale and the desktop. Now, the backdrop
should become visible in full glory. In the component graph, the new component
appears connected to the "GUI". A click on the component reveals further
information along with the options to remove it from the system or to
restart it.

[image sculpt_24_04_backdrop_selected 42%]

As a next step, let us add a window system. In the '+' menu, you can find
a readily packaged window system at _GUI_ -> _themed wm_.
After installing the package, you are asked to take five decisions:

The _GUI (focus)_ should be assigned to "keyboard focus" to put the
window manager in charge of controlling the keyboard focus, which is part
of its job after all.
The _GUI_ should be assigned to "system GUI server" as the basic mechanism
to be used for graphical output and user input for the windowed applications.
By assigning _Report (shape)_ to _pointer shape_, we allow the window
manager to report information about mouse-pointer shapes.
By assigning _Report (clipboard)_ to _global clipboard_, we grant the
window manager the right to change the content of the global clipboard.
Vice versa, by assigning _ROM (clipboard)_, we permit the window manager
to obtain clipboard content.

After adding the component, the "themed wm" will appear in the components view.
To give the window system a quick try, add the small demo you can find at
_Demos_ -> _nano3d_ and assign its _GUI_ to our "themed wm".
You will be greeted with the window as follows.

[image sculpt_ce_nano3d 40%]

Next, let us add a *small Unix-like subsystem* called _system shell_ hosted in
a window. This subsystem will be presented in a terminal window. The font
used by the terminal is obtained from a font server. To create the font
server, install and add the package _GUI_ -> _fonts fs_, and
assign the _system font configuration_ to its _ROM (config)_. "ROM" means
read-only memory. So we grant the font server read-only access to the system's
default font configuration (which is generated automatically according to the
screen resolution).

For starting the actual system shell, select and install
_Tools_ -> _system shell_ from the menu. The configuration
dialog is a bit more elaborate this time.

:GUI: defines the GUI server that should host the terminal.
  Select "themed wm".

:File system (config): defines which file system should be mounted at
  _/config/_ inside the instance. There exist a number of options.
  By selecting _writeable system configuration_, we grant control over
  the whole system. It goes without saying that this should not be done
  light-heartedly. However, since we trust the "system shell" package from
  Genode Labs, let's do it.

:File system (report): defines the file system to be mounted at _/report/_
  inside the instance. By selecting "read-only system reports", we allow
  the instance to look at the state of various parts of the system.

:File system (target): defines a file system to be mounted at _/rw/_.
  This can be any file system you'd like to work with or explore, for
  example the "ram fs".

:File system (fonts): defines the place where to obtain the font used by
  the terminal. Select the "fonts fs" component we have started earlier.

:ROM (vimrc): defines the configuration for the vim text editor used
  within the instance. Select "default vim configuration" to grant
  read-only access to this information.

:ROM (clipboard): defines the service to obtain clipboard content from.
  Select "themed wm" (not "global clipboard").

:Report (clipboard): defines the service for reporting new clipboard content.
  Select "themed wm". More information about the integration and use of the
  clipboard can be found in
  [https://genodians.org/nfeske/2019-07-03-copy-paste - a dedicated article].

:Region maps:
  Select "custom virtual memory objects" to allow the subsystem to manage
  its virtual memory layout by itself.

With those decisions taken, a fresh system shell can be started, which appears
in a window.

[image sculpt_20_08_system_shell 60%]

When selecting the "system shell" component in the graph, the
relationship to the other components of the system is presented. This provides
a convenient way to reveal the _trusted computing base_ of the selected
component.
For example, since there is no connection from _system shell_ to the
_nic_router_, we know that this component is isolated from the network. The
network-related components are outside the trusted computing base of the
system shell.

[image sculpt_24_04_system_shell_selected 50%]


Using a persistent storage device
=================================

The steps described above used an in-memory file system (ram fs) as target for
Sculpt OS, which is a nice playground for experimentation but otherwise
impractical for real-world use because all downloads and configurations
vanish when rebooting the system.

Sculpt OS supports USB storage, NVMe, and SATA (AHCI) as storage target. Only
one target can be selected for use at a time. To select one of those targets for
use, make sure to have deselected the "Use" button of the "ram fs" component.

The following steps describe the use of the USB stick that holds the Sculpt
OS boot image as target. The USB stick can be accessed be selecting the "usb"
component.

[image sculpt_24_04_usb_selected 50%]

Upon selecting the USB stick, one can see three partitions. The first two
partitions are necessary for booting from the stick whereas the third
partition labeled "GENODE" is designated as Sculpt storage target.
This partition is merely large enough to hold the system image of about 30 MiB,
but there is no room for additional data yet.
When selecting the 3rd partition, the dialog offers several management
operations.

[image sculpt_24_04_usb_operations 50%]

One can use the "Expand" operation to enlarge the partition up to the
capacity of the storage device,

[image sculpt_24_04_usb_expanding 80%]

Under the hood, the expand operation modifies the partition table and
resizes the file system, which you can observe by the additional components
at the right. Depending on the used USB stick, the resizing can take some
time. You may have a glimpse at the log window to get hold of diagnostic
messages.

[image sculpt_24_04_usb_default 50%]

Once the resizing has completed, you can see that the partition has grown to
a practical size. In principle, one can manually instruct Sculpt OS to use
this partition as storage target via the "Use" button. To automate this manual
step, the partition can be marked as preferred storage target by enabling the
"Default" button. This renames the partition to "GENODE*", which tells
Sculpt to use it automatically at boot time. By combining this automatism with
the steps described in Section [Making customizations permanent] all of your
customizations can take immediate effect at boot time.


Further exploration
===================

The presets offered in the "System" menu provide suitable starting points for
creating custom Sculpt systems. In particular the "window manager" preset
is a useful baseline for desktop-like use cases, providing a ready-to-use
window system along with a system-shell window.

Of course, there are many more components to explore and to combine.
For inspiration, please follow the postings at
[https://genodians.org], for example:

:Copy and paste mechanism:

  Sculpt provides a built-in mechanism for exchanging data between
  virtual machines, terminals, and Qt applications:

  [https://genodians.org/nfeske/2019-07-03-copy-paste]

:Use GNU/Linux inside a virtual machine on top of Sculpt:

  There is a ready-to-use package for downloading Debian for the use inside
  a virtual machine along with the ability to use VirtualBox guest
  additions:

  [https://genodians.org/jws/2019-07-08-download_debian-guest-additions-reloaded]

  For configuring and starting the virtual machine, you may find the
  following guides useful:

  [https://genodians.org/jschlatow/2022-10-27-fresh-vm-on-sculpt]

  [https://genodians.org/m-stein/2019-03-07-vm-with-sculpt-ce-preview]

  You may even go a step further by re-using an existing Linux installation
  inside VirtualBox on Sculpt:

  [https://genodians.org/jschlatow/2021-04-23-start-existing-linux-from-sculpt]

:Disposable Firefox VMs:

  Use a minimalistic Tinycore-Linux system to run Firefox in memory without
  access to any persistent storage:

  [https://genodians.org/alex-ab/2019-03-06-disposal-browser-vm]

:Advanced window management:

  The features of the "window system" preset described in detail.
  Let Sculpt remember window positions across reboots, swap out window
  decorations on the fly, and have fun with manipulating the window layout
  directly via a textual interface.

  [https://genodians.org/nfeske/2020-03-27-window-management]

:Encrypted file store:

  The file-vault package provides Sculpt users with an easy way to set
  up and use an encrypted file store using Genode's custom Tresor block
  encrypter.

  [https://genodians.org/m-stein/2021-05-17-introducing-the-file-vault]

:Network connectivity via LTE:

  The article describes several ways of using Genode's LTE modem driver
  as network uplink.

  [https://genodians.org/jschlatow/2021-07-21-mobile-network]

:Interactive CPU frequency and power steering:

  Modern PCs provide plenty of metering and power-management options.
  The component described in the following article makes these features
  available via an interactive user interface. One can watch the temperature
  of each CPU core, monitor the individual CPU frequencies, switch between
  power profiles, and reveal details about power draw.

  [https://genodians.org/alex-ab/2023-10-23-msr]


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, one can use an
entire disk as one file system without creating a partition table.

_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.


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 hosts the most fundamental drivers needed to operate the
hardware platform. On the PC, it includes drivers for ACPI discovery,
safeguarding the access of the PCI bus, or controlling the IOMMU.
This functionality is provided to the rest of the system as a so-called
platform service. All other drivers like USB, NVMe, display, networking, or
audio are not covered by the drivers subsystem. They enter the picture at a
later stage and use the platform service to access device resources.


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.

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 access the
_config_ and _report_ file systems. Both file systems are readily accessible
under the "Files" tab of the panel. The file browser allows you to traverse
directory hierarchies, inspect individual files, and edit files.
Alternatively to the "Files" tab, Sculpt 24.04 features a command-line
interface. To spawn this command-line interface, click on the "ram fs"
component in the graph and select "Inspect". In the panel, a third tab named
"Inspect" appears, which hosts the command-line interface.

[image sculpt_23_04_inspect_tab 100%]

The inspect tab hosts a small Unix-like runtime as user interface. Don't let
the presence of a Unix shell mislead you. Sculpt is not a Unix system. It
merely uses Unix-like subsystems as convenient tools for managing and editing
files. Within the inspect tab, 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.

_Note that the interactive inspect view is not bullet-proof. Should you get_
_stuck, you may re-spawn it at any time by toggling the "Inspect" button._

Besides the interactive shell, the Leitzentrale employs a simple viewer of the
most recent diagnostic log messages. You can toggle the log display via the
panel's log button. Each line of the log is prefixed by the label of the
originating component. For detailed analysis, the complete log is also
available at _report/log_ and can be browsed with Vim in the inspect window.


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

The Leitzentrale subsystem empowers you to interactively inspect and tweak
the running system either by using the file browser hosted in the "Files"
tab or by using the command-line interface and the Vim text editor provided by
the "Inspect" tab.


Interactive file browser
------------------------

The "Files" tab of the panel switches the main screen area to a simple file
browser that lists all file systems available, in particular the _config_
and _report_ file systems.
By toggling one of the file-system buttons, the
respective directory hierarchy can be browsed. When hovering a file, an "Edit"
or "View" button appears, which can be used to open the file in a text area
that appears on the right side of the file browser. The editor supports the
usual notepad-like motions, operations, and shortcuts (control-c for copy,
control-v for paste, control-s for save).

[image sculpt_24_04_files_tab 80%]

_Note that the file browser does not_
_yet support file operations like the copying, renaming, or removal of_
_files. Also, the editing of files with long lines or the browsing of_
_directories with many entries is not appropriately covered yet. As a_
_fallback when encountering these limitations, the current version of Sculpt_
_still features the Unix-based inspect tab, which can be activated by_
_toggling the "Inspect" button inside the USB or storage nodes of the_
_component graph._


Vim skills recommended for using the inspect tab
------------------------------------------------

With the "Inspect" button toggled for at least one file system, the inspect
tab 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 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).


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

By default, Sculpt uses the US-English keyboard layout, but it offers a few
alternative keyboard layouts like French and German in the settings menu in
the upper left corner. A change of this setting is reflected in the
_config/managed/event_filter_ file, which is the configuration for the
event-filter component mentioned in Section [System overview]. For tweaking
the input processing beyond the keyboard-layout setting, copy this file to
_config/event_filter_.

! inspect:/> cp /config/managed/event_filter /config/event_filter

With the _config/event_filter_ file in place, you may notice that the
keyboard-layout menu has vanished. This is because now you have taken over
manual control. (BTW, you can get the menu back at any time by removing the
file).

As a Vim user, you most likely want to remap the useless capslock key to
escape, don't you? You can accomplish this by editing your
_/config/event_filter_ file.

! inspect:/> vim /config/event_filter

To remap the capslock key to escape, change the following line
! <key name="KEY_CAPSLOCK" to="KEY_CAPSLOCK"/>
to
! <key name="KEY_CAPSLOCK" to="KEY_ESC"/>

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

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

Take the time to review the remaining parts of the event-filter
configuration. The nested configuration nodes define a hierarchy of
filters that are applied in the order from the inside to outside
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/runtime/intel_fb/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_.

For a quick test, change the attributes 'height="768"' to 'force_height="768"'
and 'width="1024"' to 'force_width="1024"'. 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 _drivers_ at the config file system. In particular, it is interesting to
follow the '<route>' rules to see how the various components are connected,
and the '<policy>' rules that assign device resources to driver components.
Analogously to the drivers subsystem, you can find the construction plan
for the Leitzentrale subsystem at the file _leitzentrale_. Try out
the following tweaks:

* Change the transparency of the Leitzentrale 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 the file _nitpicker_. For example, you
may change the background color or the labeling color of the "default"
domain.


System resources
================

Whenever adding a new component via the '+' menu, one has to define how to
connect the component with the rest of the system. It is important to know
what the presented options mean to take educated decisions.

[image sculpt_24_04_system_shell_routing 40%]

Each choice represents a connection to a system resource of a particular type.
Initially, the presented options are resources that are built-in into Sculpt's
base system. Once new components enter the picture, their services also appear
as options.


   Resource type            | Interface      | Built-in options
  ----------------------------------------------------------------------------
  ----------------------------------------------------------------------------
   Block device             | 'Block'        | direct block-device access
  ----------------------------------------------------------------------------
   Capture                  | 'Capture'      | system GUI
  ----------------------------------------------------------------------------
                            |                | management GUI
  ----------------------------------------------------------------------------
   Device access            | 'Platform'     | wifi hardware
  ----------------------------------------------------------------------------
                            |                | network hardware
  ----------------------------------------------------------------------------
                            |                | audio hardware
  ----------------------------------------------------------------------------
                            |                | ACPI
  ----------------------------------------------------------------------------
   Direct memory-mapped I/O | 'IO_MEM'       | raw hardware access
  ----------------------------------------------------------------------------
   Direct port I/O          | 'IO_PORT'      | raw hardware access
  ----------------------------------------------------------------------------
   Direct device interrupts | 'IRQ'          | raw hardware access
  ----------------------------------------------------------------------------
   Event                    | 'Event'        | system input events
  ----------------------------------------------------------------------------
                            |                | management GUI events
  ----------------------------------------------------------------------------
   File system              | 'File_system'  | writeable system configuration
  ----------------------------------------------------------------------------
                            |                | read-only system reports
  ----------------------------------------------------------------------------
                            |                | used file system
  ----------------------------------------------------------------------------
   GPU                      | 'Gpu'          |
  ----------------------------------------------------------------------------
   GUI                      | 'Gui'          | keyboard focus
  ----------------------------------------------------------------------------
                            |                | desktop lock screen
  ----------------------------------------------------------------------------
                            |                | desktop background
  ----------------------------------------------------------------------------
                            |                | system GUI server
  ----------------------------------------------------------------------------
   Hardware virtualization  | 'VM'           | virtualization hardware
  ----------------------------------------------------------------------------
   Network                  | 'Nic'          |
  ----------------------------------------------------------------------------
   Network uplink           | 'Uplink'       |
  ----------------------------------------------------------------------------
   Play                     | 'Play'         |
  ----------------------------------------------------------------------------
   Protection domain        | 'PD'           | system PD service
  ----------------------------------------------------------------------------
   Real-time clock          | 'Rtc'          |
  ----------------------------------------------------------------------------
   Record                   | 'Record'       |
  ----------------------------------------------------------------------------
   Region maps              | 'RM'           | custom virtual memory objects
  ----------------------------------------------------------------------------
   Report                   | 'Report'       | system reports
  ----------------------------------------------------------------------------
                            |                | pointer shape
  ----------------------------------------------------------------------------
                            |                | global clipboard
  ----------------------------------------------------------------------------
   ROM                      | 'ROM'          | global capslock state
  ----------------------------------------------------------------------------
                            |                | default vim configuration
  ----------------------------------------------------------------------------
                            |                | system font configuration
  ----------------------------------------------------------------------------
                            |                | platform information
  ----------------------------------------------------------------------------
                            |                | system status
  ----------------------------------------------------------------------------
                            |                | global clipboard
  ----------------------------------------------------------------------------
                            |                | build information
  ----------------------------------------------------------------------------
   Terminal                 | 'Terminal'     | debug monitor
  ----------------------------------------------------------------------------
   Tracing                  | 'TRACE'        | system-global tracing
  ----------------------------------------------------------------------------
   USB                      | 'Usb'          | direct USB-device access



[table resources]
  Overview of system resources

Table [resources] gives an overview of the different built-in
resources and their types. The names given in the interface column correspond
to the Genode session types as found in the routing rules of the deploy
configuration or launcher definitions (Section [Runtime management]).
Let's look into each type in more detail.


GUI
~~~

The GUI service interface is provided by the low-level system GUI server
(named Nitpicker) as well as the higher-level window manager. It entails both
the ability to perform graphical output and the reception of user input. Note
that the low-level GUI server keeps its client applications isolated by
default. One application cannot see the output of other applications nor can
it sniff user input globally. One can connect multiple applications -
trusted and untrusted alike - to the low-level GUI server without fear.

However, in typical scenarios, applications don't use the bare-bones system GUI
server directly but rather employ a window manager that sits in-between the
system GUI server and the applications, and equips the system with the
notion of windows.

The base system provides three different GUI options.

:keyboard focus: grants control over the keyboard focus. It should be
  assigned to only one component, typically a window manager. However,
  in principle, another component like the _system shell_ can be connected
  to it and thereby becomes able to receive keyboard input.

:desktop lock screen: assigns the component the role of a lock screen. Once
  the component is present at the GUI, it seizes the keyboard focus and is
  able to cover the entire screen.

  _Note that - with the current version of Sculpt - global keys as defined in_
  _the nitpicker configuration are not affected by the lock screen, i.e.,_
  _as is the case with the screen key assigned to the window manager._

:desktop background: allows a component to present its graphical output
  in a dedicated layer behind all other applications. The desktop background
  cannot receive keyboard focus. But it can respond to pointer events
  (mouse clicks and motion).

:system GUI server: allows a component to perform graphical output and
  handle pointer events, but no keyboard input. It is designated as a
  base mechanism for the window manager, or for implementing GUI features
  like global overlays or status displays.

By the way, the configuration of the low-level GUI server can be found at
_/config/nitpicker_ and can be modified on the fly.


ROM
~~~

ROM stands for read-only memory. A ROM service reveals information to
its clients, but a client cannot change the information. Note that the
provided information does not need to be static. It can potentially
change over time. Whenever that happens, the ROM service informs its
clients about the availability of a new version. The base system provides
the following built-in ROM resources:

:global capslock state: the system-global state of the capslock key.
  It can be handed out to components like virtual machines to keep the
  capslock state of guest operating systems consistent with the host.

:default vim configuration: the configuration of the Vim text
  editor as used in the Leitzentrale's inspect window and managed at
  _/config/vimrc_. It allows you to customize one vim configuration at a
  central place and use this configuration consistently across Sculpt's
  inspect window and manually deployed components.

:system font configuration: is the default font configuration managed
  by Sculpt according to the current screen resolution. It is of course
  customizable by the user. By using this configuration, components can
  foster a consistent user experience regarding the display of text.

:platform information: provides details about the underlying kernel and
  hardware. Some drivers and virtual machine monitors need this information to
  take platform intrinsics like the concrete flavor of virtualization hardware
  into account. Normal applications should never need this information.

:system status: reflects the system-global power state. It is used by the
  optional ACPICA driver to respond to requests for a system reset or
  power-down.

:global clipboard: provides the current content of the global clipboard.
  The content can be accessed by a component only when the user interacts
  with the component. This prevents overly nosey components from snooping the
  clipboard content.

:build information: provides details gathered during the build process of
  the Sculpt system, like version numbers or the configured default depot
  user. It is used by the Sculpt manager and debugging-support components.

Report
~~~~~~

Report services play the counterpart of ROM services. They allow clients
to report information in a fire-and-forget fashion, but not to retrieve
information. As explained in Section [System overview], the base system
includes a report service that aggregates incoming reports into the in-memory
report file system. The incoming reports are organized according to their
origin (their session labels). By granting a component access to the _system_
_reports_, the component can contribute to this knowledge base. However,
keep in mind that Sculpt's built-in report file system is limited in size.
A misbehaving component may put the system in jeopardy by producing overly
sized reports.

:pointer shape: Reports labeled with 'shape' play a special role.
  They are routed to the mouse pointer and thereby enable graphical
  applications to suggest context-specific pointer shapes. The
  application-provided shape is shown whenever the corresponding application
  is hovered.

:global clipboard: enables components to write new content to the
  system-global clipboard. This operation, however, is restricted to the
  single component that the user currently interacts with. This prevents
  rogue components from spamming the global clipboard.


File system
~~~~~~~~~~~

A file-system service offers the storage and retrieval of data organized in
a hierarchical directory structure. Access to a file system can be restricted
to be read only. The distinction between read-only and read-writeable does
not exist per file but for the entire file-system resource.

Of course, many use cases call for finer-grained access control. This is
where intermediate _chroot_ file-system components come into play. Such
a component reduces the view on an existing file system to a specific
subdirectory, which then appears as a new file system to the application.
For examples, please review the launchers at _/config/launcher/_ such as the
_shared_fs_.

The Sculpt base system has two built-in file systems.

:writeable system configuration: corresponds to the config file system
  described in Section [System overview]. The ability to access this file
  system equals to total control over the system. Hence, never assign
  this file system to components that you don't fully trust.

:read-only system reports: allows the client to inspect the global state of
  the system. The reports found in this file system are organized in a
  directory structure that corresponds to the system structure. For example,
  all reports generated by the runtime subsystem reside within the _runtime/_
  directory. Note that this global state may contain sensible information.
  For this reason, the system reports should not be handed out to components
  that are suspected of information leakage.

The two built-in file systems reside in memory. In order to access persistent
storage, additional file-system services can be started as regular components
within the runtime subsystem. Those components, in turn, need to be connected
to the corresponding block devices.

:used file system: is the file system selected for the use of Sculpt.
  In principle, the specific file system such as "usb-1-10.3.fs" can be
  selected directly. But when moving configurations from one device to
  another, the generic "used file system" option avoids tying the component to
  a particular physical file-system name. The resulting configuration works
  regardless of where it is deployed.


Block device
~~~~~~~~~~~~

A block-device resource allows for the block-level storage and retrieval
of data whereas a block-device can be read-only or read-writeable. The base
system's built-in block service hands out the devices listed at
_/report/drivers/block_devices_ according to the label of the client's session.
The label must correspond to the name of the block device. Typically, the
built-in block service is used via manually created launchers by using a route
like this:

! <route>
!   <service name="Block"> <parent label="ahci-1"/> </service>
! </route>


Device access
~~~~~~~~~~~~~

With Sculpt, device drivers can be installed and used like any regular
component. In contrast to plain applications, however, device drivers need
to access the corresponding device hardware. This access is guarded by the
so-called platform driver hosted in the _drivers_ subsystem. The platform
driver has two purposes.
First, it uses the IOMMU to isolate devices from each other and to restrict
the reach of each device to the memory explicitly assigned to the device
(DMA buffers).
Second, it arbitrates the access of device-driver components to devices.

Regarding the latter, the platform driver differentiates categories
of drivers, namely wifi, network, audio, and ACPI. When assigning one
of those resources to a driver component, the driver will see a virtual
PCI bus with only the devices that fall in the chosen category.


USB
~~~

By connecting a component to USB, the component becomes able to access
individual USB devices. One prominent use case for the USB
resource is the direct assignment of USB devices to virtual machines.
The assignment of USB devices to components is described in
Section [Assignment of USB devices to components].


Real-time clock
~~~~~~~~~~~~~~~

The real-time clock enables a component to know what time it is. The service is
optionally provided by a package called "system clock".


GPU
~~~

Access to the GPU (graphics processing unit) service allows a component to
utilize hardware-accelerated graphics on machines that feature a GPU supported
by Sculpt. Supported are Intel GPUs of generation 8 (Broadwell) or newer.

_Note that GPU support is a very recent feature and has thereby not_
_received intensive testing yet. Please regard it as experimental and_
_use it with caution._


Region maps
~~~~~~~~~~~

The region-map service of the base system gives components a flexible way to
manage their virtual address spaces manually. This mechanism is used by a few
advanced components only, most specifically virtual machine monitors. Access
to the region-map service is not security critical. But as it is rarely
needed, it is not granted by default to limit the potential (attack) surface
of the base system as far as possible by default.


Direct memory-mapped I/O, port I/O, and device interrupts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

These low-level services are provided by Genode's core component. They
should never be needed by any regular component. Even device drivers
don't use those services directly but rather rely on the higher-level
device-access service described in Section [Device access].

However, a few special use cases demand for such low-level access. In
particular the use of ACPI functionality.

As a rule of thumb, never grant access of those resources to any component
except you know exactly what you are doing and you completely trust the
provider of the component.


Terminal
~~~~~~~~

In general, a terminal service provides a bi-directional input/output stream.
Examples are a graphical terminal, or a UART driver.

Sculpt's built-in debug monitor speaks the GDB protocol as a terminal service.
The resource-assignment dialog for adding a new component offers a debug
option as checkbox. If enabled, the new component is exposed as a debugging
target (inferior) via the GDB protocol. A debugger can be connected as a
client to the debug monitor to inspect and control all the inferiors present
in Sculpt's runtime.


Tracing
~~~~~~~

The low-level tracing interface allows a component to observe and to
manipulate all activities in the system. It should only be granted to
components that are fully trusted.


Hardware virtualization
~~~~~~~~~~~~~~~~~~~~~~~

The hardware-virtualization service allows virtual machine monitors to
leverage virtualization technology (Intel VT).


Protection domain
~~~~~~~~~~~~~~~~~

By default, each component implicitly relies on the protection-domain (PD)
mechanism provided by the operating-system kernel. However, Sculpt OS allows
for the optional interception of a component's interplay with this low-level
mechanism through another component. This is useful for dynamic CPU-load
balancing, debugging, or statistical profiling.

The option to select a protection-domain service is only displayed in the
presence of at least one component that provides a PD service. Note that
a PD service is able to exercise full control over each component that uses
the service.


Network and uplink
~~~~~~~~~~~~~~~~~~

Network services provide an interface for sending and receiving network
packets. Sculpt's Leitzentrale conveniently manages drivers for wireless (wifi)
and wired (nic) networking as well as the user-level network routing
component (nic router). So you usually see the NIC router as an option. The
NIC router multiplexes the network access among multiple network applications.
By default, it acts as a virtual NAT router, handing out a distinct IP address
to each client.

An uplink server is a connection point of a network driver, which supplies
the driver with network packets to send, and accepts incoming packets received
by the driver. In most situations, the NIC router provides this service.


Record and play
~~~~~~~~~~~~~~~

The record and play services enable components to record
and play audio. These services are typically provided by the audio mixer,
which is available as option in the '+' menu. The mixing rules are defined
at _config/launcher/mixer_.


Capture and event
~~~~~~~~~~~~~~~~~

The capture and event interfaces serve as counter parts of the GUI interface.
Whereas the GUI interface allows a client to put pixels on screen and receive
input events, the capture and event interfaces allow a client to capture the
screen and inject user-input events into the system. Normally, these
interfaces are used by graphics and input-device drivers. However, they
are also useful for remote-desktop scenarios, virtual keyboards, or for
taking screen shots.

Note that those interfaces are _security critical_. When handing out a
capture interface to a component, the component becomes able to observe the
screen content of all applications present at the GUI server. Vice versa, by
handing out an event interface to a component, the component becomes able to
inject user-input events to the GUI server, acting on behalf of the user. The
built-in choices allow a component to be connected to either the system-global
GUI server, or specifically to the management GUI.


CPU-resource assignment
~~~~~~~~~~~~~~~~~~~~~~~

[image sculpt_24_04_affinity 40%]

You may already have noticed the additional item "Resource assignment ..."
in the component-configuration dialog.
It leads to a sub menu for restricting the CPU usage of the new component. The
configuration dialog shows a matrix of CPU cores where the x-axis denotes the
physical cores and the y-axis the hyperthreads. By default, all available CPU
cores are selected. You can toggle the nodes by clicking on them. The dialog
ensures that the selection is always a rectangular area. So one click may
affect nodes other than only the clicked one.

Below the CPU-affinity matrix, the dialog allows for the selection of the
component's scheduling priority. Note that here the notion of priority refers
to hard static priorities as opposed to nice levels. That is, a high-priority
activity prevents all lower-level priorities from executing. Consequently, the
assignment of a high priority comes at the risk of starving lower-priority
components. The dialog presents four options:

:Driver:

  The highest priority should be preserved to latency-critical device drivers
  such as audio drivers. This option is also a sensible choice for trusted
  components that must stay somewhat responsive under any condition. For
  example, the components of the Leitzentrale GUI operate on this priority to
  preserve the user's control over the system even in the event of a rampaging
  high-priority device driver.

:Multimedia:

  The second-highest priority is recommended for latency-sensitive
  applications such as audio and video players as well as their dependencies.
  For example, it is the appropriate priority for window-management
  components.

:Default:

  The default priority is suitable for all regular applications as well as
  storage and networking components.

:Background:

  The lowest priority is designated for non-interactive best-effort workloads
  such as long-running computations. By assigning the background priority to
  such components, they won't impede the user's perception of the
  responsiveness of the system.

The "System control" option allows the new component to monitor or manipulate
physical parameters like CPU frequencies, power consumption, and temperatures.
Given the broad potential side effects of those parameters, this option should
only be enabled in rare special cases. Grant it only to components you trust.


Service-level sandboxing
========================

In order to deploy any component, all resources requested by the component must
be assigned to appropriate services. For example, when adding a web browser,
the browser's request for record and play sessions must be satisfied, which is
natural when consuming multimedia content. However, in other situations, we
may deliberately want to isolate the web browser from the audio hardware,
forcibly preventing the browser from producing any noise or tapping the
microphone.

This is where the so-called "black hole" component enters the picture,
which can be enabled as option in the '+' menu.
The black-hole component provides pseudo services for most
resources mentioned in the previous section, including audio, networking,
video capture, USB, and ROM. Hence, the resource requirements of an untrusted
component can be satisfied without exposing a real resource. This is
especially useful for deploying highly flexible components like VirtualBox,
which supports many host-guest integration features, most of which are
desired only in a few scenarios. For example, to shield a virtual machine from
the network, the "Network" resource of the VirtualBox instance can simply
be assigned to the "black hole".


Runtime management
==================

[image sculpt_runtime_highlighted]

In contrast to the drivers subsystem and the Leitzentrale, which have a
predefined purpose, the runtime subsystem is shaped by the user. The
components present in the runtime subsystem are displayed by the components view.
Some of them are managed by the Leitzentrale. For example, while inspecting a
file system, the corresponding "inspect" component appears automatically. Other
components correspond to subsystems deployed from installed packages, in
particular the ones created via the '+' menu.

The current configuration of the runtime subsystem is available at the
_config_ file system at _managed/runtime_. It is not recommended to modify
this file manually. However, for diagnostic purposes, it is sometimes useful to
take manual control over the runtime configuration. This is possible by
copying the file to the root of the config file system.
Note that this will inhibit the management functionality of the Leitzentrale.
You can yield back the control to the Leitzentrale by removing the _runtime_
file from the root of the config file system.

As a prerequisite for deploying user-selected components, a default storage
location must be defined by selecting the "Use" button of a file system
in the menu. For the start, it is best to select the "ram fs" as
storage location. Once you are comfortable with Sculpt, you may make the
installation and customizations permanent by using a real storage device
instead.

The selection of a "used" file system 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
from Genode Labs and Genode's individual core developers. You
may inspect the content of _/ram/depot_ using the inspect window.

With a file system and an Internet connection selected, additional software
can be installed and run. The most convenient way is the interactive use of
the '+' menu to browse the catalogs of packages provided by software
providers and to configure new component instances.

Additionally, the deployment can be controlled by the _deploy_ file of the
_config_ file system and the so-called launchers located at the _launcher/_
subdirectory.
The _deploy_ file contains a '<start>' node for each running component.
Such a <start> node specifies the package, the assigned resources,
and the rules of how the component is connected with other components.

Alternatively, a <start> node may refer to a launcher that encapsulates
this policy as a separate file at the _launcher/_ directory.
By default, the launcher corresponds to the 'name' attribute of the start node.
It is possible to explicitly refer to a differently named launcher by
specifying a 'launcher' attribute. This way, one launcher can be instantiated
multiple times.
The files within the _launcher/_ directory are monitored by Sculpt and
therefore can be edited on the fly. This is especially useful for editing
'<config>' nodes of already running components.
A '<config>' node within a launcher - when present - overrides the one
provided by the package. In turn, a '<config>' node within a node of the
deploy config overrides any other '<config>' node. Both the launcher and a
'<start>' node may contain a '<route>' node. The routing rules defined in the
'<start>' node have precedence over the ones defined by the launcher. This
way, the routing of a launcher can be parameterized at the deploy
configuration.

Each time the _deploy_ file or a launcher file is written, the change
takes immediate effect. In particular, the Sculpt manager will automatically
kick off the download of the referenced packages and its dependencies and
thereby populates the depot. Once the download has completed, the packages are
started.


Interplay of the deploy configuration and interactive changes
-------------------------------------------------------------

The content of the _deploy_ file is taken as the starting point for the
interactive use via the '+' menu. All interactive changes to the deployment
are reflected in the _managed/deploy_ file.
Note that any modification of _deploy_ resets _managed/deploy_ to the state
defined in the _deploy_ file.

Launchers appear as checkboxes at the options tab of the '+' menu,
which make them a handy way to start and stop preconfigured components.


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 supports SATA disks, NVMe devices,
SD cards, and USB-storage devices. Depending on the present block-device
controllers, Sculpt starts the driver components "nvme", "mmc", and "ahci" as needed.
A click on such a node reveals the attached block devices,
possible operations, or - if a partition table is present - more details about
the device structure.
USB storage devices can be managed at the "usb" node.

Depending on the operation selected by the user, the Sculpt manager will
automatically spawn helper components in the runtime to perform the selected
operation.
For example, by selecting the "Format device" operation, the Sculpt manager
will create a tiny Unix-like subsystem with the selected block device mounted at
'/dev/block' and e2fsprogs mounted at '/'. This Unix-like subsystem 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"
tab. 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.

The most important customization is the system composition, usually created
via the '+' menu. To make it permanent, copy the current state of
_/config/managed/deploy_ to _/<DISK>/config/<VERSION>/deploy_ where _<DISK>_
corresponds to your Sculpt partition. This deploy configuration will take
effect whenever the Sculpt partition is selected for "Use".

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:

# An entire SATA or NVMe device used as a single EXT2 file system
# Partition named "GENODE*" on a USB device in a GPT (GUID Partition Table),
# Partition named "GENODE*" on a SATA or NVMe storage device in a GPT,

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.


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,
* Keyboard-layout selection, or
* 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 overridden by manually managed 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 system. All files generated
by the Sculpt manager are located at the _managed/_ subdirectory of the
config file system. By manually creating a same-named file at the root of the
config file system, 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,
* Managing Wifi credentials manually by supplying a custom _config/wifi_ file.
* 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.

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].


Custom presets
==============

The presets available in the system menu at the upper-left screen corner
correspond to the files present at _/config/presets/_. Each file is a
_deploy_ configuration. You can turn the currently running system into
a preset by copying _/config/managed/deploy_ as new file to
_/config/presets/_.

To keep your custom preset available after reboot, follow the pattern
described in Section [Making customizations permanent] by copying the file to
_/config/24.04/presets/_ at your Sculpt partition.


Installation on disk
====================

Even though Sculpt OS is distributed as a system image for a USB stick,
the same image can be written to an NVMe or SATA disk to attain a computer
that boots directly into Sculpt OS. The easiest way is starting a live
Linux of your choice, downloading the Sculpt OS image to /tmp/, checking the
SHA256 sum of the downloaded file against the known-good value as found on the
download page, and writing the file to the block device of the disk using the
'dd' command. After booting into Sculpt OS from disk, use the interactive
dialogs in the nvme or ahci component to extend the 3rd (GENODE) partition to
make the whole disk usable and mark the partition as "default" (relabeling it
to GENODE*).

Should you prefer to set up your machine for dual-booting Linux and Sculpt OS,
you can find all information needed for supplementing a Sculpt OS boot entry
to your existing boot loader at the /boot directory of the third partition of
Sculpt's disk image.


On-target system update
=======================

The system image of Sculpt OS resides at the _/boot/_ directory of the
"GENODE" partition of the boot medium. E.g., when using a USB stick as boot
medium on the PC, the boot directory resides on the 3rd partition of the
USB stick. To update the Sculpt system image, make sure to have selected
your boot partition for "use" by Sculpt. Should your boot medium differ from
your regular Sculpt partition, e.g., when using an entire hard disk as one Sculpt
partition, you may need to "un-use" your regular Sculpt partition and
temporarily "use" your boot USB stick instead.

With having your boot medium selected for the use by Sculpt, the system menu
at the upper-left screen corner provides you with a convenient user interface
for discovering and downloading new versions, and for switching between the
installed system images.

[image sculpt_24_04_check_updates 50%]

The upper part of the dialog allows you to select the system-image provider.
By default, the provider is set to the one of your currently running system
image. But you have the option to obtain images from alternative providers,
or even add a new custom provider by using the "Edit" button. Under the
hood, each listed provider corresponds to a directory in your _depot/_ at the
sculpt partition.
When adding a custom provider, it will show up as a new directory there.
The lower part of the dialog presents the information about the currently
running system image for reference.

The check-for-updates button downloads the information about available
images from the selected provider. This information is presented along
with the already downloaded images as exemplified in the following screenshot.

[image sculpt_24_04_update 50%]

The little "..." dots indicate that change-log information is available when
clicking on the entry. The download button fetches the image. Once fetched,
the download button turns into an install button. You can select any present
image for your next boot via the corresponding install button. Under the hood,
this operation copies the content of the
_depot/<provider>/image/sculpt-<board>-<version>/_ directory to your _/boot/_
directory.
Note that you can switch back and forth between different versions this way.
For example, should a new version not behave to your full satisfaction, you
can easily switch back to the previous one by using the install button of the
original version. As a precaution, it is good to have downloaded the initial
Sculpt version you are using. In the worst case, should a new version fail to
boot, you can still manually copy this downloaded original version from your
local _depot/_ to your boot directory using a live USB system.

Once an image is installed, the dialog tells you "reboot to activate".
One way to do that is by changing the system state in _/config/system_ to
"reset".


Audio
=====

Sculpt OS supports playback and recording of audio as an optional feature
that is available at the options tab of the '+' menu. The central component is
the mixer, which provides the record and play services to the audio driver(s)
and applications.

[image sculpt_24_04_audio_options 40%]

The audio driver is a mere client of the mixer. It can be started and removed
without interfering with the liveliness of audio applications.

[image sculpt_24_04_mixer_audio 40%]

By default, the mixer keeps the microphone muted and mixes the playback of all
applications at an equal volume. This policy is defined by the mixer's
configuration at _/config/launcher/mixer_, which you can find accompanied by
instructive comments. For example, uncomment the '<play>' nodes referring to
'mic_left' and 'mic_right' to unmute the mic, or tweak the volume values.
For tweaking the configuration, it is useful to know the labels of the
clients. One can obtain this information from the mixer's report at
_/report/runtime/mixer/state_.
You can find the mixer configuration described in more detail in its
[https://github.com/genodelabs/genode/blob/master/repos/os/src/server/record_play_mixer/README - documentation].

Analogously to the mixer, the audio driver can be configured dynamically
by tweaking the values in _/config/launcher/audio_. For example, you can
find the master volume for the whole device there.


Assignment of USB devices to components
=======================================

Sculpt OS has built-in drivers for USB HID devices and USB storage devices,
which are started automatically if detected. In addition, individual USB
devices can be assigned to components such as virtual machines, webcam
drivers, or smartcard drivers. The user-defined rules for assigning USB
devices to components reside at _/config/usb_. Sculpt combines these rules
with dynamic built-in rules concerning HID and storage devices into
_/config/managed/usb_, which is the USB-driver configuration.

The _/config/usb_ file contains a few examples that can be taken as a blueprint.
The '<policy>' nodes refer to clients of the USB host controller whereas
the embedded '<device>' nodes represent assignments. The examples take the
vendor and device IDs of devices as keys for the assignment.

Note that one device may be present in multiple policies, which works well if
only one of the matching clients is running at a time. It is fine to define
rules for devices that are not present. As soon as such a device gets plugged
in, the assignment will take effect. This is useful when repeatedly plugging
and unplugging the same USB device assigned to a virtual machine.

While defining _/config/usb_ rules, it is helpful to review the currently
attached devices. This information is available at
_/report/runtime/usb/devices_.


System power control
====================

Sculpt OS offers system-power controls like reset, power-down, and standby
available as an optional feature. On PC hardware, this functionality requires
ACPI support, which can be enabled as option on the '+' menu.

[image sculpt_24_04_acpi_support 40%]

Once enabled, the "acpi support" component appears and the system menu at the
upper-left screen corner hosts interactive power controls.

[image sculpt_24_04_system_power 40%]

Caveats
-------

As suggested by the names of controls, the reset and power-down operations
take immediate effect if confirmed. Note that the file-system driver
synchronizes file modifications every 10 seconds. So take a breath before
powering down or rebooting your machine.

The standby support is highly experimental. The baseline functionality of
returning from sleep to an interactively accessible system has been tested on
machines with mixed yet promising results.

On most machines, the wifi driver is not able to re-initialize the wifi device
after resume. The Lenovo x260 is a notable exception.

Upon resume, Sculpt OS restarts the USB host-controller driver, which
implies the restart of all USB clients. E.g., a virtual machine connected
to USB will be affected. While accessing any USB storage device, the standby
option is deliberately not presented.

The NVMe, AHCI, and Intel GPU drivers are suspend-resume aware, which means
that clients of their services are expected to continue operating after
resuming from standby. The response of the file-system stack to suspend-resume
cycles is not yet thoroughly tested through.

The audio driver is not automatically restarted during the suspend-resume
cycle. You may try restarting audio manually.

The limitations will be addressed gradually over time. Feedback about the
feature on your specific machine is appreciated. Don't hesitate to post your
experience on the Genode mailing list.


Touchpad on Intel Gen11+
========================

Touchpads on recent Intel laptops are integrated as I2C HID devices without
legacy PS/2 emulation. To support such trackpads, a dedicated driver is
needed. Even though Sculpt OS has no built-in trackpad driver, it offers
an I2C HID driver as an option in the '+' menu. Of course, you will need to
use a USB mouse to initially activate and configure this option.

The driver needs to know a few platform-specific values that must be manually
configured at _/config/launcher/trackpad_. The configuration is annotated with
known values for several laptop models. Adjust the configuration by using the
values matching your hardware and restart the touchpad driver to let the new
configuration take effect.


Building the boot image
=======================

The following steps assume that you have the Genode tool chain installed on a
GNU/Linux system. For reference, Ubuntu LTS is known to work well. If you
don't know your way around Genode's source tree yet, please consider the
"Getting started" section of the Genode Foundations book that is available to
download at [https://genode.org].

# Clone Genode's Git repository:

  ! git clone https://github.com/genodelabs/genode.git
  ! cd genode
  ! git checkout -b sculpt-24.04 sculpt-24.04

# Download the support for the NOVA microkernel

  ! ./tool/depot/download genodelabs/bin/x86_64/base-nova/2024-04-26

  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/2024-04-26 \
  !    genodelabs/pkg/x86_64/sculpt_drivers-pc/2024-04-26

# 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 'libports', 'ports', 'pc', 'dde_linux',
  'dde_rump', and 'dde_bsd' repositories 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.

  You may also consider enabling parallel build by uncommenting the
  corresponding line at the top of the file.

# Prepare GRUB 2, which is needed for booting from the disk image

  ! ./tool/ports/prepare_port grub2

# 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 BOARD=pc DEPOT=omit

  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.


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

Section [Building the boot image] presents the creation of the boot image
from pre-built packages. You may prefer 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 \
!      acpica bash coreutils curl dde_bsd dde_rump e2fsprogs-lib \
!      expat freetype gdb gmp gnupg grub2 jitterentropy jpeg \
!      libarchive libc libdrm libgcrypt libiconv libnl libpng \
!      libssh libusb libuvc libyuv linux linux-firmware mesa \
!      ncurses nova openssl qemu-usb qoost qt5 stb stdcxx \
!      ttf-bitstream-vera vim virtualbox6 wpa_supplicant \
!      x86emu xz zlib

To be able to compile components that are dependent on the Qt5-library, the
corresponding toolchain needs to be installed in addition to the base Genode
toolchain. You can build and install it by using the following commands:

! <GENODE-DIR>/tool/tool_chain_qt5 build
! <GENODE-DIR>/tool/tool_chain_qt5 install

The ingredients of the boot image are defined by the _sculpt/default-pc.sculpt_
file located in the _repos/gems/_ repository. The default set of software
installable at runtime is subsumed by the 'pkg/sculpt_distribution' and
'pkg/sculpt_distribution-pc' packages. You can find the depot recipes for these
packages at _repos/gems/recipes/pkg/_. You may want to create your version of
these packages 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 boot image including all required depot packages, it's best to
instruct the build system to manage the versioning and updating of the depot
content automatically by enabling the following line in your _build.conf_
file.

! RUN_OPT += --depot-auto-update

With these precautions taken, the execution of the _sculpt.run_ script - as
described in Section [Building the boot image] - implicitly builds all required
binary packages from source.

The 'sculpt_distribution' and 'sculpt_distribution-pc' packages can be
created independently of the _sculpt.run_ script by using the 'depot/create'
tool manually.

! <GENODE-DIR>/tool/depot/create \
!      UPDATE_VERSIONS=1 FORCE=1 REBUILD= \
!      <YOU>/pkg/x86_64/sculpt_distribution \
!      <YOU>/pkg/x86_64/sculpt_distribution-pc

The 'FORCE=1' argument ensures that source archives are re-created and
checked for the consistency with their versions. Whenever the source code of any
archive changes, 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.

To make the created packages available for download from within the running
Sculpt system, you must publish them. This involves the archiving, signing, and
uploading of the content. The former two steps are covered by the
_tool/depot/publish_current_ tool. For more information about working with the
depot tool, refer to the package-management
[https://genode.org/documentation/developer-resources/package_management - documentation].

The launchers integrated in the boot image are defined in
_gems/sculpt/default-pc.sculpt_ and the accompanied files at
_gems/sculpt/launcher/_. Each launcher contains a node with a mandatory 'pkg'
attribute. If the attribute value contains one or more '/' characters, it is
assumed to be a complete pkg path of the form '<USER>/pkg/<NAME>/<VERSION>'.
Otherwise, it is assumed to be just the pkg name and is replaced by the current
version of the current depot user's pkg at system-integration time.

The following article gives further inspiration and practical hints for
customizing the Sculpt OS system image.

:Crafting a modded Sculpt OS image in a few moderate steps:

  [https://genodians.org/nfeske/2023-11-10-modding-sculpt]


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 greatly benefits from the
free-software/open-source community. The following projects play a particularly
important role for Sculpt OS.

:NOVA microhypervisor:

  Sculpt's kernel is a derivate of NOVA, maintained by Genode Labs.
  NOVA was originally created by Udo Steinberg [https://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)_

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

:OpenBSD:
  [https://www.openbsd.org]
  _(basis for the audio driver)_

:libusb:
  [https://libusb.info]
  _(used by the webcam driver)_

:libuvc:
  [https://ken.tossell.net/libuvc/doc/]
  _(used by the webcam driver)_


Programs and libraries used within the Unix-like subsystems
-----------------------------------------------------------

:Vim:
  [https://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)_

:Jitterentropy RNG:
  [https://chronox.de/jent.html]


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

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


Libraries used for the graphical user interface
-----------------------------------------------

:libpng:
  [http://www.libpng.org/pub/png/libpng.html]
  _(used for decoding PNG images)_

:stb:
  [https://github.com/nothings/stb]
  _(used for rasterizing TrueType fonts)_

:Mesa 3D:
  [https://mesa3d.org]
  _(used for hardware-accelerated 3D graphics)_


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:
  [https://core.tcl-lang.org/expect/index]

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

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