[core] Issues running in native mode with `PLATFORM_DRM` in Bullseye in RPI Zero W

[raysan5]

I'm trying to run raylib in native mode in RPI Zero W with latest RPI OS Bullseye and KMS driver. After installing required libraries (libgles2-dev, libgbm-dev, libdrm-dev), compilation works ok but program crashes on run:

pi@raspberrypi:~/raylib/examples $ ./core/core_basic_window
INFO: Initializing raylib 4.1-dev
INFO: Supported raylib modules:
INFO:     > rcore:..... loaded (mandatory)
INFO:     > rlgl:...... loaded (mandatory)
INFO:     > rshapes:... loaded (optional)
INFO:     > rtextures:. loaded (optional)
INFO:     > rtext:..... loaded (optional)
INFO:     > rmodels:... loaded (optional)
INFO:     > raudio:.... loaded (optional)
INFO: DISPLAY: No graphic card set, trying platform-gpu-card
INFO: DISPLAY: Failed to open platform-gpu-card, trying card1
INFO: DISPLAY: Failed to open graphic card1, trying card0
INFO: DISPLAY: Selected DRM connector mode 1280x720 (1280x720p@60)
INFO: DISPLAY: Device initialized successfully
INFO:     > Display size: 1280 x 720
INFO:     > Screen size:  1280 x 720
INFO:     > Render size:  1280 x 720
INFO:     > Viewport offsets: 0, 0
INFO: GL: Supported extensions count: 52
INFO: GL: OpenGL device information:
INFO:     > Vendor:   Broadcom
INFO:     > Renderer: VC4 V3D 2.1
INFO:     > Version:  OpenGL ES 2.0 Mesa 20.3.5
INFO:     > GLSL:     OpenGL ES GLSL ES 1.0.16
INFO: GL: VAO extension detected, VAO functions loaded successfully
INFO: GL: NPOT textures extension detected, full NPOT textures supported
INFO: GL: ETC1 compressed textures supported
INFO: TEXTURE: [ID 1] Texture loaded successfully (1x1 | R8G8B8A8 | 1 mipmaps)
INFO: TEXTURE: [ID 1] Default texture loaded successfully
INFO: SHADER: [ID 1] Vertex shader compiled successfully
INFO: SHADER: [ID 2] Fragment shader compiled successfully
INFO: SHADER: [ID 3] Program shader loaded successfully
INFO: SHADER: [ID 3] Default shader loaded successfully
INFO: RLGL: Render batch vertex buffers loaded successfully in RAM (CPU)
INFO: RLGL: Render batch vertex buffers loaded successfully in VRAM (GPU)
INFO: RLGL: Default OpenGL state initialized successfully
INFO: TEXTURE: [ID 2] Texture loaded successfully (128x128 | GRAY_ALPHA | 1 mipmaps)
INFO: FONT: Default font loaded successfully (224 glyphs)
INFO: RPI: Opening input device: /dev/input/event1 (mouse )
INFO: RPI: Opening keyboard device: /dev/input/event0
WARNING: RPI: Failed to open Gamepad device, no gamepad available
INFO: TIMER: Target time per frame: 16.667 milliseconds
ERROR: DISPLAY: Failed GBM to lock front buffer
Segmentation fault
pi@raspberrypi:~/raylib/examples $

The system is properly configured to run on native mode with Full KMS acceleration enabled:

sudo raspi-config > Advance Options > A2 GL Driver > G2 GL (Full KMS) OpenGL desktop driver with full KMS

Driver is properly enabled in /boot/config.txt

# Enable DRM VC4 V3D driver
dtoverlay=vc4-kms-v3d
max_framebuffers = 2
gpu_mem = 256

In case it is relevant, user permissions have been reviewed:

sudo usermod -a -G render pi

The output is the HDMI, it should be the default output and it seems to be detected correctly:

INFO: DISPLAY: No graphic card set, trying platform-gpu-card
INFO: DISPLAY: Failed to open platform-gpu-card, trying card1
INFO: DISPLAY: Failed to open graphic card1, trying card0
INFO: DISPLAY: Selected DRM connector mode 1280x720 (1280x720p@60)
INFO: DISPLAY: Device initialized successfully

The error is related to function gbm_surface_lock_front_buffer() -> ERROR: DISPLAY: Failed GBM to lock front buffer.

Any idea?

EDIT: useful info: https://symbolibre.org/graphics-acceleration-on-the-raspberry-pi-zero.html

[gen2brain]

Are you in GUI mode but switched to virtual terminal or plain console? You can try to switch boot mode from Desktop to CLI in raspi-config.

[raysan5]

Additional info when trying to run glxinfo:

pi@raspberrypi:/dev/dri $ glxinfo
Error: unable to open display

[raysan5]

@gen2brain No GUI mode, console only. I'm in RPI OS Lite with no desktop environment.

[gen2brain]

Ok, I don't think glxinfo is relevant here as there is no X.
Edit: you can install/compile https://github.com/kraxel/drminfo to get more info about drm.

[raysan5]

It was reported by users it worked ok for them... but not for me. In any case, I'm closing the issue. Feel free to reopen if you find it and you face the same problem than me.

[raysan5]

After lot of investigation, one user in Discord found the solution to this issue!

In boot/config.txt, gpu_mem should be commented or set to a value lower than 256 (i.e 64 or 128)

In that case, it works as expected!

[almostobvious]

For me it was making sure to have dtoverlay=vc4-fkms-v3d and not dtoverlay=vc4-kms-v3d in /boot/config.txt.

[raysan5]

@almostobvious Afaik, vc4-fkms-v3d refers to the Fake-KMS device and the corrrect mode is vc4-kms-v3d (native-KMS). Are you trying to compile for PLATFORM_DRM with a windowing system (X11/Wayland) initialized?