Re: how to resume GRUB2 upgrade apparently blocked by /boot filesystem type=ext2?

[Andrei Borzenkov]

05.02.2016 06:22, Jordan Uggla пишет:
> 
>> 2. As part of that enablement, I should first update my
>> {`/dev/sda3`, `/boot`} from filesystem type=ext2 to something
>> else.
> 
> Definitely not.
> 
> There is no filesystem for which it really makes sense to install 
> grub's boot sector to a partition, and with ext3 and ext4 you will
> get an identical error. With btrfs you wouldn't get this error
> messages, as btrfs allows for a reliable embedding area, but your
> BIOS will still load the code in your MBR, so that's where grub's
> boot sector should be installed.
> 

There are other opinions :)

a) MBR does not have any formal specification to set aside space for
bootloader and mark is as used, so other software may go ahead and
overwrite bootloader.

b) having bootloader in partition makes it easy to switch between
installed operating systems by just flipping active partition bit.
Syslinux MBR code allows booting from logical partition as well which
removes limit on number of bootable OS instances you may have (or gptmbr
which removes restriction as well).

c) Known problem with Windows is that it may insist on having "correct"
MBR during installation of some updates and overwrite it, removing
installed GRUB (or fail update installation).

So each has its pros and cons and at the end it is up to user to decide.