[Bug 1893227] [NEW] Scrambled display with newer grubx64.efi bootloader and terminal_output gfxterm

[Alexandros Afentoulis]

Public bug reported:

Hello and thanks for maintaining grub in Ubuntu.

We've been using grub EFI boot loader in Bionic and Focal official cloud
images. After upgrading grub packages from 2.02-2ubuntu8.14 to
2.02-2ubuntu8.17 we are having trouble with console display (provided by
QEMU VNC) as it is scrambled and unreadable. See attached screenshot.

We have noticed that the problem manifests itself when terminal_output
is set to "gfxterm" but is not present when set to "console".
Additionally we verified that in Bionic the problem manifests itself
with boot loader provided by 1.93.19+2.02-2ubuntu8.17 (sha1sum:
7be316b0542921956dc3742d70b26e409ca83ef0
/boot/efi/EFI/BOOT/grubx64.efi) while the boot loader provided by
1.93.15+2.02-2ubuntu8.14 (sha1sum:
2895a67157d97b0d3825987639d817a08aad3da8 /boot/efi/EFI/BOOT/grubx64.efi)
works just fine.

Problem manifests itself in Focal hosts as well featuring grub-efi-
amd64-signed version 1.142.4+2.04-1ubuntu26.2.

Boot loader and related files are installed by grub in
/boot/efi/EFI/BOOT/ during the image creation like this:

```
grub-install  --boot-directory=/boot --efi-directory=/boot/efi --target=x86_64-efi --removable --uefi-secure-boot --no-nvram
```

said invocation among other things does copy files provided by grub-efi-amd64-signed package:
```
grub-install: info: copying `/usr/lib/grub/x86_64-efi-signed/gcdx64.efi.signed' -> `/boot/efi/EFI/BOOT/grubx64.efi'.
grub-install: info: copying `/usr/lib/shim/shimx64.efi.signed' -> `/boot/efi/EFI/BOOT/BOOTX64.EFI'.
grub-install: info: copying `/usr/lib/shim/mmx64.efi' -> `/boot/efi/EFI/BOOT/mmx64.efi'.
grub-install: info: copying `/usr/lib/shim/BOOTX64.CSV' -> `/boot/efi/EFI/BOOT/BOOTX64.CSV'.
grub-install: info: copying `/boot/grub/x86_64-efi/load.cfg' -> `/boot/efi/EFI/BOOT/grub.cfg'.
```

A naive experimentation, swapping the old boot loader in place of the
newer, restores display back to normal.

We will be happy to provide more details if needed.

** Affects: grub2-signed (Ubuntu)
     Importance: Undecided
         Status: New

** Attachment added: "Screenshot_2020-08-27_17-20-38.png"
   https://bugs.launchpad.net/bugs/1893227/+attachment/5405198/+files/Screenshot_2020-08-27_17-20-38.png

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https://bugs.launchpad.net/bugs/1893227

Title:
  Scrambled display with newer grubx64.efi bootloader and
  terminal_output gfxterm

Status in grub2-signed package in Ubuntu:
  New

Bug description:
  Hello and thanks for maintaining grub in Ubuntu.

  We've been using grub EFI boot loader in Bionic and Focal official
  cloud images. After upgrading grub packages from 2.02-2ubuntu8.14 to
  2.02-2ubuntu8.17 we are having trouble with console display (provided
  by QEMU VNC) as it is scrambled and unreadable. See attached
  screenshot.

  We have noticed that the problem manifests itself when terminal_output
  is set to "gfxterm" but is not present when set to "console".
  Additionally we verified that in Bionic the problem manifests itself
  with boot loader provided by 1.93.19+2.02-2ubuntu8.17 (sha1sum:
  7be316b0542921956dc3742d70b26e409ca83ef0
  /boot/efi/EFI/BOOT/grubx64.efi) while the boot loader provided by
  1.93.15+2.02-2ubuntu8.14 (sha1sum:
  2895a67157d97b0d3825987639d817a08aad3da8
  /boot/efi/EFI/BOOT/grubx64.efi) works just fine.

  Problem manifests itself in Focal hosts as well featuring grub-efi-
  amd64-signed version 1.142.4+2.04-1ubuntu26.2.

  Boot loader and related files are installed by grub in
  /boot/efi/EFI/BOOT/ during the image creation like this:

  ```
  grub-install  --boot-directory=/boot --efi-directory=/boot/efi --target=x86_64-efi --removable --uefi-secure-boot --no-nvram
  ```

  said invocation among other things does copy files provided by grub-efi-amd64-signed package:
  ```
  grub-install: info: copying `/usr/lib/grub/x86_64-efi-signed/gcdx64.efi.signed' -> `/boot/efi/EFI/BOOT/grubx64.efi'.
  grub-install: info: copying `/usr/lib/shim/shimx64.efi.signed' -> `/boot/efi/EFI/BOOT/BOOTX64.EFI'.
  grub-install: info: copying `/usr/lib/shim/mmx64.efi' -> `/boot/efi/EFI/BOOT/mmx64.efi'.
  grub-install: info: copying `/usr/lib/shim/BOOTX64.CSV' -> `/boot/efi/EFI/BOOT/BOOTX64.CSV'.
  grub-install: info: copying `/boot/grub/x86_64-efi/load.cfg' -> `/boot/efi/EFI/BOOT/grub.cfg'.
  ```

  A naive experimentation, swapping the old boot loader in place of the
  newer, restores display back to normal.

  We will be happy to provide more details if needed.

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