[Buildroot] EGLFS Could Not Find DRM Device!
Charles Steinkuehler
charles at steinkuehler.net
Sun Aug 29 03:03:40 UTC 2021
> Hello Scott,
>
> On Wed, 18 Aug 2021 20:28:12 +0000, Scott Bartolett <SBartolett at thorlabs.com> wrote:
>
>> Yes I have the BR2_PACKAGE_RPI_FIRMWARE_INSTALL_DTB_OVERLAYS enabled and rpi-firmware/overlays entry in genimage. If I search the buildroot output folder I find this:
>>
>> ./output/images/rpi-firmware/overlays/vc4-kms-v3d.dtbo
>> ./output/images/rpi-firmware/overlays/vc4-kms-v3d-pi4.dtbo
>> ./output/build/rpi-firmware-1a46874494146f470d7a61b0b6f4f15a07dd8b35/boot/overlays/vc4-kms-v3d.dtbo
>> ./output/build/rpi-firmware-1a46874494146f470d7a61b0b6f4f15a07dd8b35/boot/overlays/vc4-kms-v3d-pi4.dtbo
>>
>> But I do not find those files anywhere on the target machine. I am using a root file system overlay. Might that be my problem?
>
> The overlays are stored in the first/boot partition (vfat one where the dtb files,
> config.txt and cmdline.txt, bootcode.bin and start.elf and fixup.dat and zimage
> are found) and not on the second/root (ext4 one with the complte root file system)
> partition of the SD card...
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?
--
Charles Steinkuehler
charles at steinkuehler.net
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