firmware Bug no firmware reserved region can cover this RMM

unfortunately, after a full battery discharge, one laptop (Asus Zenbook running with Kubuntu) had a major problem: at startup the two following messages appear

• [firmware Bug] no firmware reserved region can cover this RMRR
• [firmware Bug] ACPI region does not cover the response buffer the laptop boots but cannot be used since the screen is completely fuzzy

After multiple attempts (fsck on the partitions, complete Kubuntu reinstallation without any success), I have read in this site DMAR firmware bug. Broken BIOS? the possibility of adding two lines in the grub: intremap=no_x2apic_optout nox2apic. acpi=off if the system starts complaining about ACPI.

I've tried but this doesn't work when updating the grub. It's possible that my syntax was inaccurate. Help would be very appreciated! Thanks edit Below, find the grub file, could you tell me if somethings could be enhanced?

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
#GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="intremap=no_x2apic_optout nox2apic"
GRUB_CMDLINE_LINUX=""

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console


acpi=off

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

While booting up into 20.04 from an external USB hard-disk on my Lenovo T420 I received firmware Bug announcement referring to no caching page found etc.

I then shutdown (long-press on power button) and ran Ubuntu 20.04 installed on the laptop. As a sudo-user I ran fsck to check the USB drive's file-system status. The /boot file-system needed the dirty-bit cleaned. The remaining file-systems were all OK.

After a clean shutdown and reboot from the external USB drive I was able to enter and update the residing Ubuntu 20.04.

So, maybe worth checking the integrity of a drive's file-systems first before investigating other possibilities. The firmware Bug indication made no hint of a file-system problem. It could be argued that the hard-power-off action may have well caused damaged to the /boot region but after cleaning there was no firmware Bug error reported.

Peter