[Bug 1828273] Re: Framebuffer setting in GRUB_CMDLINE_LINUX_DEFAULT has no effect

The framebuffer is created by the kernel and not GRUB, reassigning

** Summary changed:

- Framebuffer setting in GRUB_CMDLINE_LINUX_DEFAULT has no effect
+ User cannot disable boot framebuffer creation

** Also affects: linux (Ubuntu)
Importance: Undecided
Status: New

** No longer affects: grub2 (Ubuntu)

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https://bugs.launchpad.net/bugs/1828273

Title:
User cannot disable boot framebuffer creation

Status in linux package in Ubuntu:
New

Bug description:
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)

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