Re: How to exit from linux kernel and return to then grub?

[SevenBits <sevenbitstech@gmail.com>]

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Actually, a correction to what I just said. A processor can return
from protected mode to real mode. Read more here:

https://en.wikipedia.org/wiki/Protected_mode#Entering_and_exiting_protected_mode

I don't know if GRUB supports this (I would assume not) but generally
speaking it is still not possible to do what you want because the
Linux kernel as far as I know does not have the functionality that
would be required. If you want to try and do this, go ahead and
attempt it, but the roadblocks will be so large that it probably is
not worth trying, and just simply rebooting the machine is the best
way to get to GRUB.

If you tell us what are _trying_ to do, i.e what you need this
functionality for, perhaps we can suggest an alternative way to
achieve what you need.

- -- SevenBits

P.S: Since this topic is not about the development of GRUB, it
probably doesn't belong in this list. Please consider posting to
grub-users instead.

On 05/18/2014 01:33 AM, Z C wrote:
> If I boot into a linux kernel using a grub command like "linux
> /vmlinuz; inirtd /initrd; boot", how do I shutdown linux itself
> (but do not power off or reboot the computer hardware) and return
> back to the grub directly?
> 
> What I meant is something equivalent to the "exit" command in most
> shells: If you are within one shell and you enter another shell,
> then if you want to quit the second shell and return back to the
> first shell, just simply type exit. All env variables and commands
> you previous typed in the first shell are completely intact.
> 
> Suppose I am now in the grub shell, and then I boot into a tiny
> linux kernel, say, a busybox shell, then what can I do to exit the
> second shell (i.e. busybox shell) and return to the first shell
> (i.e. grub shell)? Of course I can enter the grub shell again by
> simply rebooting the hardware, but this is not what I want.
> 
> 
> 
> _______________________________________________ Grub-devel mailing
> list Grub-devel@gnu.org 
> https://lists.gnu.org/mailman/listinfo/grub-devel
> 
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