grub-pc versus grub-efi-amd64

[Tom H]

On Sat, Aug 29, 2020 at 5:31 PM Volker Wysk <post at volker-wysk.de> wrote:
>
> I've completely reinstalled and set up my UEFI system anew, a few
> weeks ago. Now I'm wondering why the package grub-pc and not
> grub-efi-amd64 is installed. I have two GPTs (SSD and HDD) and a
> partition which is larger than 2 GB on the HDD, and it works.
>
> On the page [1] there it's written about the GRUB customizer program:
>
> "Dieser Artikel basiert auf dem Paket grub-pc für ältere BIOS-Rechner
> bzw. Installationen im BIOS-Modus. Auf modernen EFI-Systemen wird
> dagegen das Paket grub-efi-amd64 eingesetzt. Während das bei einfachen
> Aufgaben keine Rolle spielt, kann ein Neuschreiben des MBR
> (BIOS-Modus) ein EFI-System schwer beschädigen!"
>
> I couldn't find an English version. Here's my translation:
>
> "This article is based on the package grub-pc for elder BIOS-computers
> or rather installation in BIOS mode. On modern EFI systems however
> the package grub-evi-amd64 is used. Whereas this doesn't play a role
> for simple tasks, a new-writing of the MBR (BIOS mode) can damage an
> EFI- system severely."
>
> Why is grub-pc installed on my system, and not grub-efi-amd64? Why
> does it work at all..??
>
> What happends when I run Grub Installer? Will that nuke my new system?
> What happends when I install grub-efi-amd64?

I installed 20.10 right after 20.04 was released on an EFI system, and
I also have "grub-pc" rather than "grub-efi-amd64" installed.

The Ubuntu grub2 source package's chopped up into many binary packages.

Neither "grub-pc" nor "" have anything really significant for booting
an EFI system.

localhost /tmp/GRUB $ dpkg -L grub-pc
/.
/usr
/usr/bin
/usr/lib
/usr/lib/grub-legacy
/usr/lib/grub-legacy/update-grub
/usr/sbin
/usr/sbin/upgrade-from-grub-legacy
/usr/share
/usr/share/bash-completion
/usr/share/bash-completion/completions
/usr/share/bug
/usr/share/bug/grub-pc
/usr/share/bug/grub-pc/presubj
/usr/share/bug/grub-pc/script
/usr/share/doc
/usr/share/man
/usr/share/man/man8
/usr/share/man/man8/grub-bios-setup.8.gz
/usr/bin/grub-ntldr-img
/usr/sbin/grub-bios-setup
/usr/share/bash-completion/completions/grub-bios-setup
/usr/share/doc/grub-pc

localhost /tmp/GRUB $ apt download grub-efi-amd64

localhost /tmp/GRUB $ dpkg -x grub-efi-amd64_2.04-1ubuntu28_amd64.deb .

localhost /tmp/GRUB $ lr
.:
grub-efi-amd64_2.04-1ubuntu28_amd64.deb  usr/

./usr:
share/

./usr/share:
bug/  doc/

./usr/share/bug:
grub-efi-amd64/

./usr/share/bug/grub-efi-amd64:
presubj  script*

./usr/share/doc:
grub-efi-amd64@

localhost /tmp/GRUB $ sudo apt install grub-efi-amd64 -s
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  grub-gfxpayload-lists grub-pc
The following NEW packages will be installed:
  grub-efi-amd64
0 upgraded, 1 newly installed, 2 to remove and 0 not upgraded.
Remv grub-gfxpayload-lists [0.7] [grub-pc:amd64 ]
Remv grub-pc [2.04-1ubuntu28] [grub-efi-amd64-signed:amd64 ]
Inst grub-efi-amd64 (2.04-1ubuntu28 Ubuntu:20.10/groovy [amd64])
Conf grub-efi-amd64 (2.04-1ubuntu28 Ubuntu:20.10/groovy [amd64])
th localhost /home/th

localhost /tmp/GRUB $

So if you install "grub-efi-amd64", nothing much'll change.