The userland repository of the Pi Foundation contains several libraries to communicate with the RPi’s GPU and use GPU related actions such as mmal, GLES and others. It also contains the camera functions such as raspivid and raspistill.
Sync RPi with the XCS. This ensures all symbolic links will be corrected.
XCS~$ $XC_RPI_BASE/rpicross_notes/scripts/sync-rpi-xcs.sh rpizero-local-root
Download userland
XCS~$ mkdir -p $XC_RPI_ROOTFS/usr/src/
XCS~$ cd $XC_RPI_ROOTFS/usr/src/
XCS~$ git clone https://github.com/raspberrypi/userland.git --depth 1
The
userlandrepository is downloaded inrootfsbecause themake installdoes not copy the headers of the libraries.
Create the build location for userland and run CMake.
XCS~$ mkdir -p $XC_RPI_ROOTFS/usr/src/userland/build/arm-linux/release
XCS~$ cd $XC_RPI_ROOTFS/usr/src/userland/build/arm-linux/release
XCS~$ cmake \
-D CMAKE_TOOLCHAIN_FILE=$XC_RPI_BASE/rpicross_notes/rpi-generic-toolchain.cmake \
-D CMAKE_BUILD_TYPE=Release \
-D ARM64=OFF \
$XC_RPI_ROOTFS/usr/src/userland/
This should produce an output similar to:
-- The C compiler identification is GNU 4.9.3
-- The CXX compiler identification is GNU 4.9.3
-- Check for working C compiler: /usr/bin/arm-linux-gnueabihf-gcc
-- Check for working C compiler: /usr/bin/arm-linux-gnueabihf-gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/arm-linux-gnueabihf-g++
-- Check for working CXX compiler: /usr/bin/arm-linux-gnueabihf-g++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for execinfo.h
-- Looking for execinfo.h - found
-- The ASM compiler identification is GNU
-- Found assembler: /usr/bin/arm-linux-gnueabihf-gcc
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.1")
-- Configuring done
-- Generating done
-- Build files have been written to: /home/pi/rpi/rootfs/usr/src/userland/build/arm-linux/release
Next, make userland.
XCS~$ make -j 4
-j 4tells make to use 4 threads, which speeds up the process.
Install the created libraries:
XCS~$ make install DESTDIR=$XC_RPI_ROOTFS
Remove build and git files from the src (these are not needed on the RPi)
XCS~$ cd $XC_RPI_ROOTFS
XCS~$ rm -rf $XC_RPI_ROOTFS/usr/src/userland/build
XCS~$ rm -rf $XC_RPI_ROOTFS/usr/src/userland/.git*
Sync the updated “rootfs” with the RPi:
XCS~$ $XC_RPI_BASE/rpicross_notes/scripts/sync-xcs-rpi.sh rpizero-local-root
Testing the compiled userland-libraries is done by building our own version of raspicam and creating a picture. Note that this test requires that the RPi has a camera connected and that you have links2 installed.
Create the build-dir and build the application
XCS~$ mkdir -p $XC_RPI_BUILD/hello/raspicam
XCS~$ cd $XC_RPI_BUILD/hello/raspicam
XCS~$ cmake \
-D CMAKE_TOOLCHAIN_FILE=$XC_RPI_BASE/rpicross_notes/rpi-generic-toolchain.cmake \
$XC_RPI_BASE/rpicross_notes/hello/raspicam
XCS~$ make
Sync and run.
XCS~$ scp hellocam rpizero-local:~/
XCS~$ ssh -X rpizero-local
RPI~$ ./hellocam -v -o testcam.jpg
"hellocam" Camera App (commit Not found)
Camera Name imx219
Width 3280, Height 2464, filename testcam.jpg
Using camera 0, sensor mode 0
GPS output Disabled
Quality 85, Raw no
Thumbnail enabled Yes, width 64, height 48, quality 35
Time delay 5000, Timelapse 0
Link to latest frame enabled no
Full resolution preview No
Capture method : Single capture
Preview Yes, Full screen Yes
Preview window 0,0,1024,768
Opacity 255
Sharpness 0, Contrast 0, Brightness 50
Saturation 0, ISO 0, Video Stabilisation No, Exposure compensation 0
Exposure Mode 'auto', AWB Mode 'auto', Image Effect 'none'
Flicker Avoid Mode 'off'
Metering Mode 'average', Colour Effect Enabled No with U = 128, V = 128
Rotation 0, hflip No, vflip No
ROI x 0.000000, y 0.000000, w 1.000000 h 1.000000
Camera component done
Encoder component done
Starting component connection stage
Connecting camera preview port to video render.
Connecting camera stills port to encoder input port
Opening output file testcam.jpg
Enabling encoder output port
Starting capture -1
Finished capture -1
Closing down
Close down completed, all components disconnected, disabled and destroyed
RPI~$ links2 -g testcam.jpg
As a result, a window should be opened and show a snapshot of the camera.
Depending on the size of the image, this may take a while.
userland:../../../../lib/libvcos.so: undefined reference to `_dl_init_static_tls'
../../../../lib/libvcos.so: undefined reference to `_dl_pagesize'
../../../../lib/libvcos.so: undefined reference to `__pointer_chk_guard_local'
../../../../lib/libvcos.so: undefined reference to `__dlclose'
../../../../lib/libvcos.so: undefined reference to `__dlerror'
../../../../lib/libvcos.so: undefined reference to `_dl_stack_flags'
../../../../lib/libvcos.so: undefined reference to `__dlopen'
../../../../lib/libvcos.so: undefined reference to `__dlsym'
../../../../lib/libvcos.so: undefined reference to `_dl_wait_lookup_done'
../../../../lib/libvcos.so: undefined reference to `__pthread_create'
If such message appear during building (make) it might be because you need to fix the symlinks of the RPi-filesytem. Try building after syncing (and make sure you remove all build files):
XCS~$ $XC_RPI_BASE/rpicross_notes/scripts/sync-rpi-xcs.sh rpizero-local-root
...
XCS~$ cd $XC_RPI_ROOTFS/usr/src/userland/
XCS~$ rm -rf build/*
XCS~$ mkdir -p $XC_RPI_ROOTFS/usr/src/userland/build/arm-linux/release
XCS~$ cd $XC_RPI_ROOTFS/usr/src/userland/build/arm-linux/release
XCS~$ cmake \
-D CMAKE_TOOLCHAIN_FILE=$XC_RPI_BASE/rpicross_notes/rpi-generic-toolchain.cmake \
-D CMAKE_BUILD_TYPE=Release \
-D ARM64=OFF \
$XC_RPI_ROOTFS/usr/src/userland/
XCS~$ make
links2:Could not initialize any graphics driver. Tried the following drivers:
x:
Can't open display "(null)"
fb:
Could not get VT mode.
Check if there is a warning upon login on the RPi. If you see “Warning: untrusted X11 forwarding setup failed: xauth key data not generated” you might need to use the “-Y” instead of “-X” option when connecting via SSH.