Comment 3 for bug 1779092

FYI. I am hit by this problem too. Updated system in Synaptic on 26th which included
Upgrade: amd64-microcode:amd64 (2.20131007.1+really20130710.1, 3.20180524.1~ubuntu0.14.04.1)

Had previously installed (2 weeks ago) linux-image-extra-3.13.0-151-generic:amd64 (3.13.0-151.201)

Now system hangs with black screen. Running in recovery mode the last two lines are
x86: Booting SMP configuration:
.... node #0: CPUs #1

Booting back in 3.13.0-149 works fine.

smpboot: CPU0: AMD Athlon(tm) II X4 600e Processor (fam: 10, model: 05, stepping: 02)
Gigabyte Technology Co., Ltd. GA-MA785GM-US2H/GA-MA785GM-US2H, BIOS F12a 07/08/2010

Hope this helps.