Re: Is GRUB2 customizeable enough?

[Simon Hobson]

Richard Owlett <address@hidden> wrote:

> The purpose AND rationale SHALL be that the default OS choice *SHALL BE* the 
> first OS installed.
> 
> WHY?
> No matter how badly I mess up, a "hard reset/cold boot" shall *ALWAYS* boot 
> to a known working OS.

There's a way to achieve this - sort of.
Slightly modify the files in (rom memory) /etc/grub that build grub.cfg. 
Arrange for your primary "safe" OS to have a distinct label, then set that 
label as the default OS.

That won't prevent installing/modifying another OS from clobbering grub.cfg - 
but neither will *any* other method that relies on a specific grub config. Thus 
there is absolutely no possibility of building a system that fits your needs of 
"No matter how badly I mess up" simply because there is no way to prevent you 
messing up the boot partition and/or bootloader.

The only way I could see you getting that level of safety would be to have a 
separate (small) drive that has a write-protect function. Thus you make that 
your primary boot device, configure stuff, make it (or at least the bootloader 
& boot partition) read-only, and then nothing can mess it up.

You could have your primary system not have a separate /boot partition - so 
/boot for it is within it's root partition. That would help as the other OSs 
you install/modify won't see a boot partition and so won't clobber it - but 
they can still clobber the bootloader. This would also mean you'd need to 
reboot into you safe system every time there's a need to update grub.cfg - but 
that's a good idea anyway as ideally you only ever want one system in charge of 
it.