Comment 9 for bug 1787260

This may have been a BIOS bug, does not occur after BIOS upgrade (BIOS P4.70 04/17/2018 -> BIOS L4.81 08/16/2018):

# dmesg -t | grep ^DMI:
DMI: To Be Filled By O.E.M. To Be Filled By O.E.M./X370 Taichi, BIOS L4.81 08/16/2018

# dmesg | grep -A5 'efifb: probing for efifb'
[ 0.813333] efifb: probing for efifb
[ 0.813342] efifb: framebuffer at 0xe0000000, using 19456k, total 19456k
[ 0.813344] efifb: mode is 3440x1440x32, linelength=13824, pages=1
[ 0.813345] efifb: scrolling: redraw
[ 0.813347] efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0
[ 0.820746] Console: switching to colour frame buffer device 430x90