I had to manually downgrade plymouth 0.9.2 to 0.8.8-r4 because the drivers options were removed, and the new libkms useflag specifically lists in the documentation not to support the radeon graphics cards.
Where is that documentation?
Taken straight from equery output: $ equery uses plymouth * Found these USE flags for sys-boot/plymouth-0.9.2: + - libkms : Provides abstraction to the DRM drivers (intel, nouveau and vmwgfx at this moment) $ equery uses sys-boot/plymouth-0.8.8-r4 * Found these USE flags for sys-boot/plymouth-0.8.8-r4: + - libkms : Provides abstraction to the DRM drivers (intel, nouveau and vmwgfx at this moment) - - video_cards_intel : VIDEO_CARDS setting to build driver for Intel video cards - - video_cards_radeon : VIDEO_CARDS setting to build driver for ATI radeon video cards (P.S. output truncated and taken from a different machine)
We are not doing anything special to this, upstream disabled that support many time ago: https://cgit.freedesktop.org/plymouth/commit/?id=8e932e9895bacf9b490e60e4be63d8902201e5d5 and I see other distributions using this version without issues. I would report this to upstream directly (maybe you need to configure plymouth in some way with your radeon setup :/) https://bugs.freedesktop.org/enter_bug.cgi?product=plymouth&GoAheadAndLogIn=Log%20in
