Testing libcamera on Virtme

By Kaaira Gupta
libcamera

What this blog is about

This write-up highlights how one can use Virtme, which is a QEMU wrapper used to run a virtualized Linux kernel, to test the changes made in libcamera on the latest kernel.

Virtme is good in the sense that it is easy to use, and makes testing kernel changes quite simple, without having to reboot the entire system again and again. I will walk through how we can use qcam, which is a testing application of libcamera, inside virtme.

The steps

  • Follow https://libcamera.org/getting-started.html to clone and compile libcamera on your native machine.
  • Clone latest media_tree using: 
      git clone git://linuxtv.org/media_tree.git
  • Install virtme: 
      pip3 install --user git+https://github.com/ezequielgarcia/virtme.git
  • Compile Kernel with Virtme: 
    • cd media_tree
virtme-configkernel --defconfig
    • Enable vimc/vivid/ etc as per requirement
    • Enable CONFIG_DRM_VIRTIO_GPU=y in kernel config
    • make -j8
  • Run virtme (on native machine)
    • Use a variable to pass memory and CPUs to be used by QEMU to prevent Out of Memory error. Adjust the values accordingly. 
      export MEM_CPU="-m 2G -smp 2"
    • Run virtme 
      virtme-run --graphics --kdir $KDIR --kopt="console=ttyS0" --qemu-opts $MEM_CPU -vga virtio -serial mon:stdio

      where $KDIR is kernel directory’s path

  • To run qcam (in virtme): 
      QT_QPA_PLATFORM=linuxfb /usr/local/bin/qcam