https://bugzilla.kernel.org/show_bug.cgi?id=205049
--- Comment #7 from Lukáš Krejčí (lskrejci@gmail.com) --- Ok, because of the automatic line wrapping, I'll make the example shorter:
change this:
linux /vmlinuz-3.17.4-301.fc21.x86_64 ro initrd /initramfs-3.17.4-301.fc21.x86_64.img
to this:
linux /vmlinuz-3.17.4-301.fc21.x86_64 ro amdgpu.ppfeaturemask=0xffff3fff initrd /initramfs-3.17.4-301.fc21.x86_64.img