On 7/31/20 6:35 AM, Alan McRae via CentOS wrote:
I am running an Intel x64 machine using UEFI to boot an SSD.
Installing the latest yum update which includes grub2 and kernel 4.18.0-193.14.2.el8_2.x86_64 renders the machine unbootable, blank screen where grub should be, no error messages, just hangs.
... The main point of this message is to make people aware of the problem and suggest admins don't run 'yum update' until they understand the problem and have a fix at hand.
I posted, on 7/30, to CentOS-devel the following after my similar experience (booting an mSATA SSD on my M6700, with two 2.5 SATA drives (a 1TB and a 2TB), and the mSATA is not /dev/sda on this hardware, FWIW):
"Moral of the story? Have the install DVD on a USB stick and available to boot into rescue mode, know how to boot rescue mode (from the installer boot menu select 'troubleshooting....' then 'rescue....' and option 1 once the menu shows), know how to activate network interfaces in text mode (either nmcli or nmtui works fine for this), and know a few basic dnf commands. And have an alternate means of doing basic web searches available; my android phone this morning was used for that....."
I was able to recover with the install DVD on a USB stick and using rescue mode on a laptop with only WiFi (nmtui does a great job for this sort of thing, booted into rescue mode and chrooted onto /mnt/sysimage).