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

[Ralf Mardorf]

On Sat, 9 Jul 2016 15:05:11 +0200, Liam Proven wrote:
>On 8 July 2016 at 21:18, Ralf Mardorf <silver.bullet at zoho.com> wrote:
>> The do-release-upgrade only offers /dev/sda and /dev/sdb. Assumed
>> it's installed to the root fs (?partition of the root fs?), then a
>> do-release-upgrade recognises this?  
>
>
>Well, if, for example, your root FS is /dev/sda1, then all you need to
>do is:
>
>sudo grub-install /dev/sda1
>
>... and that should be it. It should write the location into its
>config file and so remember it from then on.

So there will be a pointer within the 512 bytes of the MBR, but no
entry beyond those 512 bytes, the GRUB image that might need additional
bytes, is written to some space, that belongs to the partition? It's
somewhere on the disk, but definitively not attached to the 512 bytes
of the MBR?

Regards,
Ralf