Comment 53 for bug 1851311

@Alkis Georgopoulos,

Thanks for the suggestion.
I added "rmmod tpm".
Unfortunately, it did not really help my situation...

$ sudo update-grub
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    Sourcing file `/etc/default/grub'
    Sourcing file `/etc/default/grub.d/init-select.cfg'
    Generating grub configuration file ...
    Found linux image: /boot/vmlinuz-5.3.0-51-generic
    Found initrd image: /boot/initrd.img-5.3.0-51-generic
    Found linux image: /boot/vmlinuz-5.3.0-46-generic
    Found initrd image: /boot/initrd.img-5.3.0-46-generic
    Adding boot menu entry for EFI firmware configuration
    done
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$ sudo nano /etc/grub.d/40_custom
$ sudo update-grub
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    Sourcing file `/etc/default/grub'
    Sourcing file `/etc/default/grub.d/init-select.cfg'
    Generating grub configuration file ...
    Found linux image: /boot/vmlinuz-5.3.0-51-generic
    Found initrd image: /boot/initrd.img-5.3.0-51-generic
    Found linux image: /boot/vmlinuz-5.3.0-46-generic
    Found initrd image: /boot/initrd.img-5.3.0-46-generic
    Adding boot menu entry for EFI firmware configuration
    done
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$ cat /etc/grub.d/40_custom
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    #!/bin/sh
    exec tail -n +3 $0
    # This file provides an easy way to add custom menu entries. Simply type the
    # menu entries you want to add after this comment. Be careful not to change
    # the 'exec tail' line above.

    menuentry "Install" {
        set isofile="/ubuntu.iso"
        rmmod tpm
        loopback loop (hd0,2)$isofile
        linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile noprompt noeject
        initrd (loop)/casper/initrd
    }
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Prior to this change, I would get a blank screen with a whirring fan.

With the above change, I do see the boot-up log messages.
But, I get a busy box...
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    BusyBox v1.301 (Ubuntu 1:1.30.1-4ubuntu4) built-in shell (ash)
    Enter 'help' for a list of built-in commands.

    (initramfs) Begin: Running /scripts/casper-premount ... done.
    Begin: waiting for devs... ... done.
    touch /dev/.initramfs/lupin-waited-for-devs: No such file or directory
    stdin: Invalid argument
    done.
    loop: can't get info on device /dev/loop1: No such device or address
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I don't know why it is referencing "loop1" ?