How to restore the MBR after do-release-upgrade?

[Ralf Mardorf]

On Sun, 10 Jul 2016 23:50:13 +1000, blind Pete wrote:
>I don't think that the kernel does depend on grub.

recommends of
http://packages.ubuntu.com/xenial/linux-image-4.4.0-28-lowlatency
and
http://packages.ubuntu.com/xenial/linux-image-4.4.0-28-generic
are
  grub-pc [amd64]
  GRand Unified Bootloader, version 2 (PC/BIOS version)
  or grub-efi-amd64
  GRand Unified Bootloader, version 2 (EFI-AMD64 version)
  or grub-efi-ia32
  GRand Unified Bootloader, version 2 (EFI-IA32 version)
  or grub
  GRand Unified Bootloader (Legacy version)
  or lilo
  LInux LOader - the classic OS boot loader

I had
http://packages.ubuntu.com/wily/linux-image-4.2.0-41-lowlatency
installed and no bootloader at all, so do-release-upgrade installed the
recommended GRUB package.

On Sun, 10 Jul 2016 23:38:08 +1000, blind Pete wrote:
>What have you got?  What do you want?

Thank you for the explanation. I appreciate your effort. Unfortunately
I already know this. Btw. once startup finished and after
checking /dev/sda and /dev/sdb, there's no doubt which HDD is sda and
which is sdb, apart from this, a lot of systems, e.g. mine are very
stable, the order never changed.

What I actually want, is that Ubuntu gets rid of enforcing a bootloader
install and I would like to fix the FreeBSD install. GRUB does
chainload the FreeBSD loader, but most likely during the Ubuntu release
upgrade something went wrong, now the FreeBSD loader can't mount a
slice anymore. The FreeBSD install is installed to /dev/sda1.

Regards,
Ralf