As can be seen in the board status[1] the current code triggers the respective assertion: ASSERTION FAILED: file 'src/vendorcode/amd/agesa/f16kb/Proc/GNB/Modules/GnbInitKB/GfxSamuInitKB.c', line 165
There exists a related patch[2] in gerrit and it works for me (i.e., my IMB-A180-H boots and graphics still work but the error message is gone). I am unable to quickly determine any consequences... shall we merge it? Why wasn't it yet?
1: http://review.coreboot.org/gitweb?p=board-status.git;a=blob;hb=HEAD;f=asrock... 2: http://review.coreboot.org/#/c/5361/