Introducing a radically componentized GUI architecture Norman Feske - - PowerPoint PPT Presentation

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Introducing a radically componentized GUI architecture Norman Feske - - PowerPoint PPT Presentation

Jul 10, 2023 46 likes •428 views

Introducing a radically componentized GUI architecture Norman Feske < norman.feske@genode-labs.com > Outline 1. Starting point 2. Ingredients 3. Challenges and solutions 4. Next steps Introducing a radically componentized GUI

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Introducing a radically componentized GUI architecture

Norman Feske <norman.feske@genode-labs.com>

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Outline

  • 1. Starting point
  • 2. Ingredients
  • 3. Challenges and solutions
  • 4. Next steps

Introducing a radically componentized GUI architecture 2

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Outline

  • 1. Starting point
  • 2. Ingredients
  • 3. Challenges and solutions
  • 4. Next steps

Introducing a radically componentized GUI architecture 3

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Starting point - Genode

→ Application-specific TCB

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Starting point - Nitpicker

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Starting point - Nitpicker

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Starting point

Starting point Low-complexity GUI server (nitpicker) Toolkits

◮ Qt5 ◮ DOpE ◮ Custom widget set

Hard-wired policy Goal → Desktop environment Retain low TCB complexity Accommodate a great variety of use cases

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Outline

  • 1. Starting point
  • 2. Ingredients
  • 3. Challenges and solutions
  • 4. Next steps

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ROM session interface

ROM server ROM client

session

ROM module

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ROM session interface (2)

ROM server ROM client

session

ROM module

update signal

new version

Transactional update of a ROM session

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ROM session interface (3)

Init Backdrop FS-ROM RAM FS Noux Runtime Editor config ROM file system file system

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ROM session interface (4) Demo

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Report session interface

Existing mechanisms for propagating information Configuration defined at startup Policy defined at session-creation time Session interfaces Dynamic configuration changes What is needed in addition? Components need to publish internal state, e. g.,

◮ Driver: Report available device resources ◮ Component: Report feature set ◮ Applications: User notifications ◮ Propagating error conditions Introducing a radically componentized GUI architecture 13

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Report session interface (2)

Report server Report client

session

RAM

  • report

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Publisher-subscriber mechanism

Combining “Report” and “ROM” session interfaces The report rom server provides

◮ “Report” service ◮ “ROM” service

Stores reports using report-session labels as keys Controls access using ROM-session labels as selectors Triggers ROM-changed signals on incoming reports → Generic publisher-subscriber mechansism Composeable with existing ROM-using components Can be instantiated many times

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Outline

  • 1. Starting point
  • 2. Ingredients
  • 3. Challenges and solutions
  • 4. Next steps

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Flexibility of Nitpicker

Nitpicker’s built-in policy stands in the way New configuration concept Domains Layering → Separation of policy from the nitpicker server Pointer Status bar

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Nitpicker with built-in policies

Init Nitpicker GUI Backdrop Launchpad Browser

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Policy as external components

Init Nitpicker GUI Panel Pointer Backdrop Launchpad Browser

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Domains example Demo

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Transitions

How to smoothly toggle the visibility of the windows? Adding fading feature to the application? → Increase application complexity → Modifications needed per application Adding fading feature to nitpicker? → Increase complexity of nitpicker Solution → Move fading feature to separate component

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Transitions (2)

Init Scout Nitpicker Fader Scout

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Transitions (2) Demo

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Launcher

Starting point Demo menu (monolithic application) Based on pre-rendered PNG images Customization is labour intensive Customizable launcher Runtime-generated widgets → complex (e. g., relies on libc, libpng, zlib)

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Launcher (2)

How to keep the complexity of the launcher low? Launcher is parent of all started subsystems → belongs to the trusted computing base Appealing presentation comes with complexity Solution

  • 1. Turn launcher into a multi-component application
  • 2. Sandboxed widget-rendering component

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Launcher (3)

Init Nitpicker Launcher Fader Report ROM Menu view

Nitpicker Nitpicker ROM Report

ROM

<dialog > ... </dialog >

Report

<hover > ... </hover >

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Launcher (4) Demo

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Window management

Starting point Genode lacked a coherent window manager Application-specific window management Problem Diversity of tastes and expectations by users There is no a single solution for everyone

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Window management (2)

Init Nitpicker GUI Window Manager Panel Pointer Backdrop Launchpad Browser

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Window management (3)

De-componentized window manager Provides “Nitpicker” interface (compatibility) Layouter (defines behavior) Decorator (defines look) Layouter and decorator are sandboxed

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Window management (4)

Init Window manager Nitpicker App Report ROM

ROM Report

Decorator Layouter

Nitpicker Nitpicker

ROM

<window -list > ... </window -list >

ROM

<hover > ... </hover >

Report

<window -layout > ... </window -layout >

ROM

<window -layout > ... </window -layout >

Report

<hover > ... </hover >

i n p u t

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Decorator Demo

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TCB complexity of window management

TCB footprint of the window manager No libc dependency Adds less than 3,500 SLOC Further TCB reduction Multiple window-manager instances Each instance assigned to a different nitpicker domain

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Screen resolutions

How to support different screen resolutions? The screen resolution used to be hard-wired at build time

◮ VESA driver configuration ◮ Background image of the matching size

Solution

  • 1. Detection heuristics in the VESA driver
  • 2. Resolution-independent backdrop
  • 3. Dynamic framebuffer mode updates

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Screen resolutions Demo

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Outline

  • 1. Starting point
  • 2. Ingredients
  • 3. Challenges and solutions
  • 4. Next steps

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Next steps

Alternative window layouters and decorators Capability-based desktop environment Using Genode for day-to-day computing

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Thank you

Genode OS Framework http://genode.org Genode Labs GmbH http://www.genode-labs.com Source code at GitHub http://github.com/genodelabs/genode

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