Qt-contributors-summit-2012-Qt-in-Embedded
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Qt Device/Embedded board support vision:
- Qt needs to work out of the box for embedded boards without having to patch Qt and mkspecs over and over again
- Provide an optimal build for the device
- Focus is on cross-compilation and not on on-target compilation
Note: Most of the stuff below is already in qtbase. -device is currently marked as 'experimental'
configure
- -device <device> specifies the device.
- Together with -sysroot and -device-option CROSS_COMPILE to specify the compiler, you will have Qt for your board!
- For example, for the raspberry-pi, all one needs to do is:
- configure -device pi -sysroot -device-option CROSS_COMPILE=/xgcc/prefix
- For example, for the raspberry-pi, all one needs to do is:
- There is mechanism to pass arbitrary device specific options (requires for most BSPs)
- Also allows us to use the same mkspec to support multiple distros (hardfp/softfp)
- Currently supported boards/devices
- ST7540, ST7108, Trident Shiner (PNX8473), Broadcom 97425, N9, beagleboard, snowball
- More information here: http://wiki.qt.io/Category:Devices
- passing options to configure like -no-neon
eglfs:
- No more depends on widgets, uses raster engine to paint widgets instead of opengl engine
- Integrated the build into configure
- hooks for board specific initialization
- screen depth, format, gl caps
- does not pollute board specific stuff into eglfs
- even has a xlib hook, so eglfs can be tested on the desktop just like wayland
- input
- eglfs now depends on evdev. Future task is to make it compile when evdev is absent but we are yet to see such a device (qnx?)
- can now be without udev, we have a static discovery
- moved to platformsupport
- eglfs loads input statically avoiding obscure args like -plugin EvdevKeyboard
- synchronized position with multiple cursors
- minimalegl is the old eglfs
- cursor support
- by default, you get a gl "composed" cursor
- supports hotspots
- hw accel on the pi, the cursor is a separate layer
- it's now CI (compile) tested
- allows creation of multiple windows and supports the surface format requested by the user
- required for context menus
- qmlscene —transparent allows one to create a transparent toplevel
- on the pi, each window is a layer. poor man's wayland
- Jorgen suggested moving large parts of code to platformsupport and move device stuff to separate repo
- Will be investigated post 5.0
directfb:
- similar hooks design as eglfs
- integrated into configure
- supports IDirectFBGL and DirectFB+EGL
- holger maintains directfb these days
pkg-config changes:
- no more a second class citizen for embedded targets unlike qt4
- -force-pkg-config was used only for xcompile builds and used to just check for environment variables.
- Checks PKG_CONFIG_LIBDIR instead of PKG_CONFIG_PATH since the latter pulls in host paths. Checks PKG_CONFIG_SYSROOT_DIR
(no)pkg-config works for all builds, default 'auto'- pkg-config env variables are now stored as part of qdevice.pri ("session")
configure:
- -sysroot now being actively tested and it also documented
- Saves it's output into config.summary
- Fixed QPA plugin detection
- -qpa foo sets the default qpa
- Still have the problem of runtime of autodetection
- Decided that this was unnecessary
What's coming
- Hardware image decoding for the pi (based on openmax IL – girish)
- Layer based video rendering for the pi (based on openmax IL – johannes)
- qdoc documentation
- passing options to configure like -no-neon
- Host tools when xcompiling
- Support for host compilation with -device
- Out of the box serial port configuration with QSerialPort
What's missing from Qt4/Embedded support
- linuxfb needs to be resurrected
- openvg backend
- wayland will be suggested for multiprocess support, eglfs for single process