Development with Qtfor Windows CE

10/11/09

Agenda

• Introduction to Windows CE

• How to build Qt for Windows CE

• Windows CE 5 memory model

• Ways to more memory

• Demonstration

What is Windows CE?

• OS for embedded devices

• not derived from desktop Windows

• monolithic kernel

• highly configurable using Platform Builder

• runs on x86, ARM, SH4 and MIPS

3

The world of Windows CE

• Windows CE 5.2– Windows mobile 5, 6, 6.1, 6.5

• SmartPhone (standard)• PocketPC (classic / professional)

• Windows CE 6.0 R2– Microsoft Auto– Windows mobile 7?

4

Desktop Windows vs. Windows CE

• UTF16 string representation

• No NTFS support → no file security model• No file drives• No current directory• Only 32 processes• Only 32 MB memory per process (CE < 6)

5

Desktop Windows vs. Windows CE

• Number of threads limited to system resources– no more free memory → no more threads

• API is a Win32 API subset– no *A functions– no asynchronous file I/O or network– incomplete standard C libs

6

Desktop Windows vs. Windows CE

• Situation gets better with Windows CE 6– Up to 1 GB process memory– More than 32K processes– Improved system call performance– New product name:

Windows embedded CE

7

What do you need for development?

• Visual Studio 2005 Standard or

Visual Studio 2008 Professional

• Windows CE SDK for your device

• Qt for Windows CE from qt.nokia.com

• Perl for using out-of-source builds

• Qt Visual Studio Add-in from qt.nokia.com

8

Development work flow

• Prototype on Desktop Windows

• Switch to a Windows CE Qt build

• Build, deploy and run

– Not everybody in the team needs a

Windows CE development environment.

9

How to build Qt for Windows CE?

• Use shadow builds.

C:\Qt\4.6.0\qtsource\win32\wincewm60professional\wince50standard-x86

10

How to build Qt for Windows CE?

Open a Visual Studio command prompt.Add C:\Qt\4.6.0\wincewm60professional\bin to PATH.

cd C:\Qt\4.6.0\wincewm60professional.\qtsources\configure -xplatform wincewm60professional-msvc2008 -signature mysignature.pfx

Creates Qt configuration and builds the host tools:• qmake, moc, uic, rcc• setcepaths / checksdk• cetest (if Remote API is in INCLUDE, LIBS)

11

How to build Qt for Windows CE?

...only two steps left...

setcepaths wincewm60professional-msvc2008

nmake

12

Qt DLL sizes

Qt library Size in MB

QtCore4.dll 1.67 MB

QtGui4.dll 5.67 MB

QtNetwork4.dll 0.53 MB

QtWebKit4.dll 6.86 MB

qjpeg4.dll 0.12 MB

sum 14.85 MB

Library sizes of Qt 4.5.2 on Windows mobile 6 professional:

13

The Windows CE 5.0 memory model

Slot 0

Slot 1

Slot 2

Slot 3

current process

bundled DLLs

Process 1

Process 2

Slot 32 Process 32

...

large memory area

Slot 63 Resource only DLLs • only 32 MB per slot• Application stack & heap grow from slot's bottom• DLLs are loaded into process slots top-down• DLLs are guaranteed to have the same address in every slot

14

The Windows CE 5.0 memory model

Bundled DLLs

Load address for new DLLs

15

The Windows CE 5.0 memory model

Qt DLLs

Stack & heap

16

Ways to more Virtual Memory

• Reduce the DLL size• Use static linking• Load small DLLs first• Switch to Windows mobile 6.1

17

Reducing Qt DLL sizes

• Exclude the features you don't need• “feature” = set of classes (e.g.

GraphicsView)• define QT_NO_FEATURENAMEconfigure -D QT_NO_FEATURENAME

• add this define to your application .pro fileDEFINES += QT_NO_FEATURENAME

• Tedious stuff! Is there no easier way to do this?

18

Reducing Qt DLL sizes using qconfig

Reducing Qt DLL sizes using qconfig

In your desktop Windows Qt build directory:

md tools\qconfigcd tools\qconfigqmake ..\..\..\tools\qconfig\qconfig.pronmake releaserelease\qconfig.exe

20

Reducing Qt DLL sizes using qconfig

Good candiates for exclusion:

• Standard dialogs (color, font, input, wizard, …)

• Convenience widgets (QCalendarWidget, ...)

• Clipboard, drag and drop, shortcuts

• QtConcurrent, FTP, QSystemTrayIcon

• GraphicsView for QWidget only applications

• MDI

21

Reducing Qt DLL sizes using qconfig

• Open the features description file in

src\corelib\global\qfeatures.txt• Unselect unwanted features

• Save the result in

src\corelib\global\qconfig-myfeatures.h• Reconfigure Qt

configure -qconfig myfeatures ...

22

Reducing Qt DLL sizes

standard

small

minimal

0 1 2 3 4 5 6

1.67

1.67

1.42

5.67

4.18

2.43

QtCoreQtGui

23

Accessing the Large Memory Area

• just 32 MB? Are you serious?• there's more behind slot 32• use memory mapped files• use the VirtualAlloc API

24

Accessing the Large Memory Area

Using memory mapped files:• acquire memory at 64 K boundaries QFile memfile("myfile.bin"); memfile.open(QIODevice::ReadWrite); memfile.resize(1024*1024*2); uchar* buf = memfile.map(0, 1024*1024*2); ... memfile.unmap(buf); memfile.remove();

25

Accessing the Large Memory Area

Using VirtualAlloc:• Reserve memory at 64 K boundaries or commit reserved memory at 4 K boundaries

void* ptrBase = VirtualAlloc(0, dwSize, MEM_RESERVE, PAGE_NOACCESS);buffer = VirtualAlloc(ptrBase, dwSize, MEM_COMMIT, PAGE_READWRITE);...VirtualFree(ptr, dwSize, MEM_DECOMMIT);VirtualFree(ptr, 0, MEM_RELEASE);

26

Demonstration

Questions and Answers