https://bugs.freedesktop.org/show_bug.cgi?id=93895
--- Comment #10 from Azari azari4096@gmail.com --- (In reply to Alex Deucher from comment #7)
Check your xorg log and make sure acceleration is enabled.
It seems that acceleration disables itself after the first startx attempt locks up the GPU:
[ 326.027] (--) RADEON(0): Chipset: "SUMO2" (ChipID = 0x9644) [ 326.027] (II) RADEON(0): GPU accel disabled or not working, using shadowfb for KMS [ 326.027] (II) Loading sub module "shadow" [ 326.027] (II) LoadModule: "shadow" [ 326.027] (II) Loading /usr/lib/xorg/modules/libshadow.so [ 326.047] (II) Module shadow: vendor="X.Org Foundation" [ 326.047] compiled for 1.18.0, module version = 1.1.0 [ 326.047] ABI class: X.Org ANSI C Emulation, version 0.4 [ 326.047] (II) RADEON(0): KMS Color Tiling: disabled [ 326.047] (II) RADEON(0): KMS Color Tiling 2D: disabled [...] [ 326.247] (WW) RADEON(0): Direct rendering disabled [ 326.247] (II) RADEON(0): Acceleration disabled [...] [ 326.252] (II) AIGLX: Screen 0 is not DRI2 capable [ 326.252] (EE) AIGLX: reverting to software rendering [ 326.329] (II) AIGLX: enabled GLX_MESA_copy_sub_buffer [ 326.331] (II) AIGLX: Loaded and initialized swrast [ 326.331] (II) GLX: Initialized DRISWRAST GL provider for screen 0
The full log is in this attachment: https://bugs.freedesktop.org/attachment.cgi?id=121448
I also uploaded another xorg log from the first attempt that causes the lockup, in case you want to see the difference between the two or something.