Embedded_Linux

This repo will contain some projects that I've faced during learning Embedded Linux.

• If you have a problem with HDMI in RPI-4 :

  • config.txt content :

    max_framebuffers=2 force_hotplug=1 hdmi_force_hotplug:0=1 #hdmi_safe=1 config_hdmi_boost=4 hdmi_group:0=1 hdmi_mode:0=4 #arm_64bit=0 boot_delay=1

  • cmdline.txt content : video=HDMI-A-1:1024x768@60D

• I had a problem for not booting and stucking at image of raspberry

  • Add to config.tst kernel=yourImage.img

• Problem : end kernel panic not syncing attempted to kill init raspberry It happened because the kernel tries to run systemd code. running file /sbin/init show us a 64 bit executable. so kernel tries to run 64-bit on 32-bit image.

  • The solution is to delete /sbin/init

• problem : Entering in initramfs : solution : fix the rootfs in your cmdline.txt

• problem : not detecting wlan0 ? solution : add arm_64bit=0 solution 2 : add the right modules for the right (uname -r)

• problem in not connecting to the wayland [20:28:57.062406] [C] Failed to connect to Wayland display. No such file or directory

export XDG_RUNTIME_DIR=/run/user/1001 export WAYLAND_DISPLAY=wayland-0

The problem was actually 3 separate issues stacked on top of each other:

1. Missing -audiodev link (first problem) Your original command had -device es1370 but no -audiodev backend. QEMU was emulating the sound card but had nowhere to send the audio — it was just discarding it silently.
2. Yocto's QEMU was compiled without PulseAudio support When we added -audiodev pa,id=agl, it failed with Parameter 'driver' does not accept value 'pa' because the Yocto-built QEMU binary was compiled without PulseAudio support. Your host runs PulseAudio, so ALSA couldn't reach your speakers either, giving the -5 Input/output error.
3. Wrong QEMU binary The fix was replacing the Yocto QEMU binary with a symlink to your system's /usr/bin/qemu-system-x86_64 (installed via apt), which IS compiled with full PulseAudio support.

The winning combination:

• System QEMU (/usr/bin/qemu-system-x86_64) → has PulseAudio support
• device es1370 → the virtual sound card the guest can see
• audiodev pa,id=agl → routes audio to your host's PulseAudio
• audiodev=agl → links the card to the backend

//////////////////////////////////////////////////////////////////////// runqemu - ERROR - Failed to run qemu: qemu-system-x86_64: -audiodev pa,id=agl: Parameter 'driver' does not accept value 'pa' runqemu - INFO - Cleaning up

ln -sf /usr/bin/qemu-system-x86_64
/media/abdu/LinuxHome/Embedded_Linux/git_ignoring/AGL/trout/qemux86-64/tmp/work/x86_64-linux/qemu-helper-native/1.0/recipe-sysroot-native/usr/bin/qemu-system-x86_64

runqemu qemux86-64 serial qemuparams="-device intel-hda -device hda-duplex,audiodev=agl -audiodev pa,id=agl"

root@qemux86-64:~# gst-launch-1.0 audiotestsrc wave=sine freq=440 num-buffers=100 ! alsasink device=hw:0,0

//////////////////////////////////////////////////////////////////////////

root@qemux86-64:~# aplay -l **** List of PLAYBACK Hardware Devices **** card 0: AudioPCI [Ensoniq AudioPCI], device 0: ES1370/1 [ES1370 DAC2/ADC] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: AudioPCI [Ensoniq AudioPCI], device 1: ES1370/2 [ES1370 DAC1] Subdevices: 1/1 Subdevice #0: subdevice #0

to make the app get the sound automatically cat > /etc/asound.conf << 'EOF' pcm.!default { type hw card 0 device 0 } ctl.!default { type hw card 0 } EOF

gst-launch-1.0 audiotestsrc wave=sine freq=440 num-buffers=100 ! autoaudiosink ////////////////////////////////////////////////////////////////////////////////// root@qemux86-64:~# aplay -l aplay: device_list:279: no soundcards found...

runqemu qemux86-64 serial qemuparams="-device es1370,audiodev=agl -audiodev pa,id=agl" ////////////////////////////////////////////////////////////////////////////