How to return control to GRUB

How to return control to GRUB

[Fabian Greffrath]

Dear GRUB developers,

I take care of the Debian package 'grub-invaders'. This is a multiboot
compliant kernel-game that resembles Space Invaders, but I guess you
knew that already.

One thing that annoys me about the game is, that you cannot return to
the GRUB menu. The only chance to leave the game is rebooting the
machine.

I'd like to implement a feature that makes the game return the control
back to GRUB when the ESC key is pressed (I wrote a small patch which
called the PC-BIOS cold-boot routine as found in GRUB, but this of
course will not work with iee1275 or linuxbios). Robert Milan already
pointed me to the multiboot docs, but I did not find what I was looking
for.

Can you please help me find the information needed to implement this
feature?

Thank you very much.

Cheers,
Fabian

Re: How to return control to GRUB

[Marco Gerards]

Fabian Greffrath <fabian.greffrath@web.de> writes:

Hi,

> I take care of the Debian package 'grub-invaders'. This is a multiboot
> compliant kernel-game that resembles Space Invaders, but I guess you
> knew that already.
>
> One thing that annoys me about the game is, that you cannot return to
> the GRUB menu. The only chance to leave the game is rebooting the
> machine.

[...]

Officially, this is not possible, if you want to do something like
"return to GRUB".  Before a multiboot kernel is started, the state of
GRUB 2 is destroyed.

One solution might be switching back to real-mode, making sure the
computer is in a normal state (graphics, IRQs, memory, hardware, etc).
In that case you can just load GRUB 2 from disk and jump to it.

An alternative solution is, if the license for the game is GPLv3,
making it a GRUB 2 module ;-)

--
Marco

Re: How to return control to GRUB

[Robert Millan]

On Mon, Jan 21, 2008 at 12:06:25PM +0100, Marco Gerards wrote:
> 
> An alternative solution is, if the license for the game is GPLv3,
> making it a GRUB 2 module ;-)

I thought about that, but note that this would undermine GRUB invaders
usability as a multiboot test case.

Honestly, I think it's really good as it is now.

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What use is a phone call… if you are unable to speak?
(as seen on /.)

Re: How to return control to GRUB

[Marco Gerards]

Robert Millan <rmh@aybabtu.com> writes:

> On Mon, Jan 21, 2008 at 12:06:25PM +0100, Marco Gerards wrote:
>> 
>> An alternative solution is, if the license for the game is GPLv3,
>> making it a GRUB 2 module ;-)
>
> I thought about that, but note that this would undermine GRUB invaders
> usability as a multiboot test case.

On the other hand, this way you can truely claim it is "GRUB invaders" ;-)

> Honestly, I think it's really good as it is now.

Personally, I never used it and don't care that much :-)

--
Marco

Re: How to return control to GRUB

[Fabian Greffrath]

Thanks you for your replies!

Am Montag, den 21.01.2008, 16:07 +0100 schrieb Marco Gerards:
> Personally, I never used it and don't care that much :-)

You are right, it's good as it is now. I just liked the idea to make the
game return to GRUB and I guessed there was an easy way to implement
this (and keep the code portable).

Cheers,
Fabian