[Buildroot] EGLFS Could Not Find DRM Device!
Charles Steinkuehler
charles at steinkuehler.net
Sun Aug 29 15:28:34 UTC 2021
On 8/28/2021 10:03 PM, Charles Steinkuehler wrote:
>
> Sorry to jump in, I'm new to Buildroot and this list but I am having the
> same issue: Using a RPi4 with the latest buildroot (master pulled from
> git) and no /dev/dri/ devices show up even though config.txt contains:
>
> dtoverlay=vc4-kms-v3d-pi4
>
> ...and the overlay files are present on the first (vfat) partition.
>
> I started with the raspberrypi4_64_defconfig, switched to glibc, and
> added a few packages (mesa, kmscube, SDL2).
>
> On a whim I switched init from the busybox default to systemd (which
> also pulled in udev), and *PRESTO* I now have a /dev/dri/ folder with
> devices (after once again adding the config.txt dtoverly line for the
> kms driver)!
>
> Is there any documentation about the minimum environment needed to get
> the vc4-kms drivers running? Do I need full systemd/udev, is mdev
> enough, or should devtmpfs be working but perhaps I'm missing something
> else in the rootfs image? Is init maybe the problem vs. /dev handling?
Update on what does/doesn't work:
Busybox init + devtmpfs = FAIL
Busybox init + devtmpfs + mdev = FAIL
Busybox init + devtmpfs + eudev = WORKS
systemd + udev = WORKS
I don't know enough about mdev to know if it should be possible to get
it working vs. eudev. I may look into that in the future but right now
I'm just happy to have a system working that doesn't need to pull in all
of systemd.
For clarity, "WORKS" above means I simply add the
"dtoverlay=vc4-kms-v3d-pi4" to config.txt, boot, and running "kmscube"
at the command prompt yields the expected spinning cube. I also have a
properly populated /dev/dri, and kmscube reports it is using Broadcom
V3D 4.2 for OpenGL ES rendering.
--
Charles Steinkuehler
charles at steinkuehler.net
More information about the buildroot
mailing list