This commit added some extra groups to the systemd package which are now required by the default udev rules: https://git.buildroot.net/buildroot/commit/package/systemd/systemd.mk?id=f208cf296c2c7c049d11d15b6d0546214c4d0357 However, those groups were not added to the eudev package which causes udev to warn on boot: [ 20.702706] udevd[67]: specified group 'kvm' unknown I think both the "render" and "kvm" groups need adding.
I already have mage a fix for this bug, so I'm taking it.
Patch submitted: https://patchwork.ozlabs.org/patch/1162454/
Fixed by https://git.buildroot.org/buildroot/commit/?id=0aa66343184676482b0d77446614e332ee5ccd99. Thanks!