Recovering in graphical mode hangs on a Debian 10 VM in KVM with default video mode QXL.

[proura]

• ReaR version:
  Relax-and-Recover 2.5 / 2019-05-10
  Also tested with Relax-and-Recover 2.5-git.4014.fb23c5d7.master / 2020-06-09
• OS version: Debian GNU/Linux 10
• ReaR configuration files:

OUTPUT=PXE
OUTPUT_PREFIX=PXE
OUTPUT_PREFIX_PXE=d10cli1/PXE
OUTPUT_URL=nfs://192.168.111.170/store/d10cli1
BACKUP=NETFS
NETFS_PREFIX=BKP
BACKUP_URL=nfs://192.168.111.170/store/d10cli1

(Also tested with ISO output)

• Hardware: KVM guest (default settings)
• System architecture: x86
• Firmware: BIOS/GRUB
• Storage: local disk
• Storage layout:

NAME        KNAME     PKNAME   TRAN TYPE FSTYPE  SIZE MOUNTPOINT
/dev/sda    /dev/sda           ata  disk          10G 
|-/dev/sda1 /dev/sda1 /dev/sda      part ext4      9G /
|-/dev/sda2 /dev/sda2 /dev/sda      part           1K 
`-/dev/sda5 /dev/sda5 /dev/sda      part swap   1022M [SWAP]
/dev/sr0    /dev/sr0           ata  rom         1024M 

• Description of the issue:
  When I try to recover a Debian 10 booting from PXE the Graphical Console hangs showing strange characters in the screen.

• Workaround, if any:
  I can connect by ssh or serial port and continue with the recover. I have also seen that if I change the default video model of the VM from QXL to VGA works on Debian 10 without problems, but QXL is working ok in Debian 9.

• Attachments, as applicable:

[jsmeix]

As far as I know the ReaR recovery system output
is usually plain normal Linux console output
what one gets via the kernel command line option vga=normal
which sems to be proved in this particular case here
because things work in normal VGA mode
but not in another mode (QXL).

FWIW: For me things "just work" with KVM and QXL
on openSUSE Leap 15.1 as the virtualization host
with SLES12 and SLES15 as virtual machines.

I am not a PXE user so I don't know if there is a boot menue
when booting the ReaR recovery system in case of PXE.
Normally (e.g. when booting the ReaR recovery system from ISO)
one has a boot menue where one could specify kernel command line
options as needed for specific cases.

From what I see in the current ReaR scripts

# find usr/share/rear/ -type f | xargs grep 'vga='

usr/share/rear/output/USB/Linux-i386/300_create_extlinux.sh:
    append initrd=/$USB_PREFIX/$REAR_INITRD_FILENAME root=/dev/ram0 vga=normal rw $KERNEL_CMDLINE

usr/share/rear/output/USB/Linux-i386/300_create_extlinux.sh:
    append initrd=/$USB_PREFIX/$REAR_INITRD_FILENAME root=/dev/ram0 vga=normal rw $KERNEL_CMDLINE auto_recover

usr/share/rear/output/PXE/default/810_create_pxelinux_cfg.sh:
   append initrd=$OUTPUT_PREFIX_PXE/$PXE_INITRD root=/dev/ram0 vga=normal rw $KERNEL_CMDLINE $PXE_RECOVER_MODE

usr/share/rear/conf/templates/RESULT_usage_RAMDISK.txt:
           --command-line='root=/dev/ram0 vga=normal'

usr/share/rear/lib/bootloader-functions.sh:
    echo "append initrd=$REAR_INITRD_FILENAME root=/dev/ram0 vga=normal rw $KERNEL_CMDLINE"

usr/share/rear/lib/bootloader-functions.sh:
    echo "append initrd=$REAR_INITRD_FILENAME root=/dev/ram0 vga=normal rw $KERNEL_CMDLINE auto_recover $ISO_RECOVER_MODE"

usr/share/rear/lib/bootloader-functions.sh:
    echo "    append initrd=$PXE_INITRD root=/dev/ram0 vga=normal rw $KERNEL_CMDLINE $PXE_RECOVER_MODE"

usr/share/rear/lib/bootloader-functions.sh:
    echo "linux (tftp)/$PXE_KERNEL root=/dev/ram0 vga=normal rw $KERNEL_CMDLINE $PXE_RECOVER_MODE"

it seems the kernel command line option vga=normal is the only one that is used
and it seems in particular that vga=normal is set in case of PXE booting via
usr/share/rear/output/PXE/default/810_create_pxelinux_cfg.sh

[jsmeix]

I verified that when booting the ReaR recovery system from ISO
the ReaR recovery system kernel command line option vga=normal
is explicitly set.
Because I do not use PXE booting I cannot verify what the ReaR recovery
system kernel command line options are in case of PXE booting.

[github-actions]

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