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Presentation by Harald Fernengel held during Qt Developer Days 2009. http://qt.nokia.com/developer/learning/elearning
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Qt on Real Time OSs... or how to get your Qt app on QNX and friends 10/09/09
Contents
• Some Basics
– CPU, Operating System, Windowing System
• Hardware Acceleration
• Deeper look into...
– QNX
– VxWorks
– INTEGRITY
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Contents
Some Basics
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Qt for RTOS
• Qt for RTOS ports are Community Supported
• Not all Qt modules available
• Qt APIs available unmodified (code once...)(with few exceptions that are documented in platform notes)
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Embedded vs. Desktop
• Qt Embedded can be fine-tuned for size
– configure options, e.g. -no-script
– feature macros, e.g. QT_NO_FILEDIALOG
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Integration
• Before we can start developing, the following must be considered:
– CPU Architecture
– Operating System
– Windowing System
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Contents
CPU Architecture
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Classic layer diagram
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CPU
Opera)ng System
QtCore
Classic layer diagram + atomics
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CPU
Opera)ng System
QtCore
AtomicOperations
Classic layer diagram + atomics II
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CPU
INTEGRITY
QtCoreAtomics
Summary CPU Architecture
• Qt is CPU agnostic on operating systems that feature atomic operations– INTEGRITY, Windows CE
• Otherwise, Qt has built-in support for...– x86_64, i386, ARM, MIPS, PowerPC, SuperH, ...
• Optional: Blend and Blit optimizations (using iwMMXt, SSE, ...)
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Contents
Operating Systems
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Classic layer diagram (again)
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Hardware
Opera)ng System
QtCore
OS dependencies
• Qt Embedded is self-contained
– Build system is bootstrapped
– Requires libc, pthread, some math functions
– No other external library dependencies (like STL)
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Classic OS diagram
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Hardware
Linux
QtCore
Windows Solaris Mac OS X Symbian RTOS...
Classic OS diagram (simplified)
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Hardware
POSIX
QtCore
Win32
Operating System
• Qt supports
– Win32 (*_win.cpp files)
– POSIX (*_unix.cpp files)
• Exception: Some native calls instead of POSIX for optimization or deeper integration(for example on Symbian, Mac OS X)
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Operating System - Summary
• QtCore runs well on a POSIX compliant OS/RTOS
• Amount of required POSIX functionality varies (e.g. QT_NO_FILESYSTEM)
• Subsystems (e.g. file system) can be replaced by native calls if necessary
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Contents
Windowing Systems
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Classic layer diagram with GUI
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Hardware
Opera)ng System
Windowing System
QtGui
QtCore
Windowing Systems
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X11
QtGui
S60 Windows Mac OS X
Hardware
Linux WindowsSolaris Mac OS XSymbian RTOS...
???
Introducing QWS
• Qt contains it's own Windowing System:“Qt Windowing System” (QWS)
• Contains a compositing window manager
• Requires direct access to graphics card and input devices (mouse/touchscreen, keyboard/keypad)
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Classic layer diagram with GUI
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Hardware
Opera)ng System
QWS
QtGui
QtCore
Screen DriversInput Drivers
QWS vs. OS
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Hardware
Opera)ng System
QWS
Drivers???
QWS diagram with gfx output
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Hardware
Opera)ng System
QWS
DirectFB LinuxFB Custom VNC
Network qvW
Virtual FB
QVFB screenshot
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Embedded Windowing Systems
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X11
QtGui
Hardware
Linux WindowsSolaris Mac OS XSymbian RTOS...
QWS
QWS vs. X11
• X11– asynchronous client-server architecture, IPC
– requires additional window manager process
– complex due to lots of (optional) extensions
• QWS
– self-contained
– single process mode possible
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Contents
Hardware Acceleration
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HW Acceleration in Qt
• Qt supports OpenVG and OpenGL ES >= 2.0
• Both allow HW accelerated 2D [or 3D] painting
• However, both APIs don't define the interface to the Windowing System
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Embedded Windowing Systems
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X11
QtGui
Hardware
Opera)ng System
QWS
OpenGL (ES)OpenVG
??? ???
EGL to the rescue
• EGL is the glue layer between Windowing Systems and hardware acceleration(http://www.khronos.org/egl/)
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Embedded Windowing Systems
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X11
QtGui
Hardware
Opera)ng System
QWS
OpenGL (ES)OpenVG
???
EGL
Something still missing for QWS
• EGL is still relying on an underlying windowing system
• Works for X11, but not (out of the box) for QWS
• OpenKODE with KDui extension required
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Something still missing (2)
• OpenKODE with KDui extension is its own windowing system
• So is QWS
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Something still missing (3)
• OpenKODE with KDui extension is its own windowing system
• So is QWS
• #%^!@#!!
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Introducing Lighthouse
• Lighthouse is the new QWS
• Lighthouse is not its own windowing system
• Instead, features plug-in architecture for integrating existing windowing systems
WARNING! WORK IN PROGRESS
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Embedded Windowing Systems
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X11
QtGui
Hardware
Opera)ng System
Lighthouse
OpenGL (ES)OpenVG
EGL EGL + KD
Summary Windowing System
• QWS works well with non accelerated displays
– HW acceleration possible, but tricky
• Lighthouse works best with existing windowing systems (KDgui) with OpenGL (ES) or OpenVG
• X11 works best if the infrastructure already exists for the target board, or if co-existence with other X11 applications is required
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Summary Integration
• Before writing an application, we need to...
– consider the atomic operation support
– consider the feature set
– consider the windowing system
– consider the hardware acceleration
• If that's done, it's write once, deploy everywhere
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Contents
Demo
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Contents
A Deeper Look Into...QNX
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QNX
• QNX port is community supported– About 5 occurrences of conditional Q_OS_QNX code
• Several successful deployments
– QWS without HW acceleration
• No Photon integration
– Photon is a windowing system → collides with QWS
• Photon's X11 server not recommended
– Doesn't feature Xrender, poor rendering quality
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QWS diagram on QNX
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Hardware
QNX
QWS
io-‐display Custom VNC
Network
Experimental!
QNX - limitations
• No QSystemSemaphore, QSharedMemory
– SYSV style semaphores and shared memory missing from QNX
• No QProcess support
– Starting a process in a thread not supported
• QWS has single process GUI support only
• No Qt3Support
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QNX
• How to build (see Platform Notes - QNX)– -xplatform unsupported/qws/qnx-i386-g++
– -embedded i386
– -no-qt3support
– -qt-gfx-qnx
– -qt-mouse-qnx
– -qt-kbd-qnx
– -no-exceptions
– ...
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Contents
A Deeper Look Into...VxWorks
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VxWorks
• VxWorks port is community supported
– About 60 VxWorks specific code changes
• Several successful deployments
– X11 with OpenGL acceleration
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QtGui diagram on VxWorks
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Hardware
VxWorks
QtGui
X11
VxWorks - limitations
• No QSystemSemaphore, QSharedMemory
– No SYSV style semaphores, shared memory
• No QLibrary
– No plugins
• Only one QApplication per system
– VxWorks has flat address space
• No Qt3Support
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QNX
• How to build (see Platform Notes - VxWorks)– -xplatform unsupported/qws/vxworks-simpentium-g++
– -embedded vxworks
– -exceptions
– -no-qt3support
– ...
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Contents
A Deeper Look Into...INTEGRITY
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INTEGRITY
• Only a subset of Qt supported
• Port currently only available on request
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Contents
Thank you :)(Questions?)
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