Framebuffer setting in GRUB_CMDLINE_LINUX_DEFAULT has no effect

[John Bester]

I have an Ubuntu Server 18.04 installation with KVM and a guest OS to which a AMD video card needs to be passed through. It worked great for about 9 months and after a recent Ubuntu upgrade, efifb grabs the video card irrespective of the linux command line. The commnand line that worked before is:

GRUB_CMDLINE_LINUX_DEFAULT="amd_iommu=on iommu=pt pci_stubs=1106:3483 vga=normal nofb nomodeset video=efifb:off"

Currently, this is the command line (changes I made based on searching the web for hours):
GRUB_CMDLINE_LINUX_DEFAULT="quiet amd_iommu=on iommu=pt earlymodules=vfio-pci pci_stubs=1106:3483 vga=normal nofb nomodeset video=vesafb:off,efifb:off gfxpayload=text"

The current active kernel options (proc/cmdline)

BOOT_IMAGE=/boot/vmlinuz-4.15.0-48-generic root=UUID=a83137ad-9598-4dc2-aca9-7ab19d17d3c0 ro quiet amd_iommu=on iommu=pt earlymodules=vfio-pci pci_stubs=1106:3483 vga=normal nofb nomodeset video=vesafb:on,efifb:off gfxpayload=text

This is verified by syslog:

[ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-48-generic root=UUID=a83137ad-9598-4dc2-aca9-7ab19d17d3c0 ro quiet amd_iommu=on iommu=pt earlymodules=vfio-pci pci_stubs=1106:3483 vga=normal nofb nomodeset video=vesafb:on,efifb:off gfxpayload=text

According to one of the web sites I found, any (or all) of the following options should disable the frame buffer:

vga=normal nofb nomodeset video=vesafb:on,efifb:off

Yet, a framebuffer is still created

crw-rw---- 1 root video 29, 0 May 8 18:26 /dev/fb0

Memory locked by efifb (grep -B 5 -A 5 "26[:]00" /proc/iomem)

e0000000-fec2ffff : PCI Bus 0000:00
  e0000000-f01fffff : PCI Bus 0000:26
    e0000000-efffffff : 0000:26:00.0
      e0000000-e01effff : efifb
    f0000000-f01fffff : 0000:26:00.0
      f0000000-f01fffff : vfio-pci

Yet, vfio driver is successfully loaded for this device: (ls /sys/bus/pci/drivers/vfio-pci/)

/sys/bus/pci/drivers/vfio-pci/0000:26:00.0
/sys/bus/pci/drivers/vfio-pci/0000:26:00.1

Any help on how efifb can be blocked from loading will be greatly appreciated.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: grub2-common 2.02-2ubuntu8.13
ProcVersionSignature: Ubuntu 4.15.0-47.50-generic 4.15.18
Uname: Linux 4.15.0-47-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.6
Architecture: amd64
CurrentDesktop: GNOME
Date: Wed May 8 19:32:36 2019
InstallationDate: Installed on 2017-01-12 (846 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
SourcePackage: grub2
UpgradeStatus: Upgraded to bionic on 2018-09-27 (223 days ago)

[John Bester (stellenbosser)]

I found another comment online and tried it: I added "blacklist efifb" to /etc/modprobe.d/blacklist-framebuffer.conf. I then executed "update-initramfs -u" followed by "update-grub" and rebooted. Still no joy.

[John Bester (stellenbosser)]

Found another page stating that vga=0 should be in GRUB_CMDLINE_LINUX_DEFAULT - this does not work either.

Another page states that you should enable GRUB_TERMINAL=console, this does not work.

Another page says you should add "blacklist vga16fb" in /etc/modprobe.d/blacklist-framebuffer.conf, this does not work

Is there any way I can destroy /dev/fb0 or onload efifb after Linux has booted?

[John Bester (stellenbosser)]

Yet another comment I found said that the following would work, but it did not:
systemctl set-default -f multi-user.target

Take into account that this is Ubuntu Server 18.04. Server operating system should not rely on graphics cards, so it should be possible to boot Ubuntu Server without a framebuffer.

Is there a systemd service which I can blacklist to avoid the framebuffer being created?