Re: [RFC] Detect other software using embedding area

[Thomas Schmitt]

Hi,

Colin Watson wrote:
> [...] "embedding area" [...] 
> (setup): When embedding the core image in a post-MBR gap, [...]
 
Aka "hidden blocks" ?

> several people followed up to say that GRUB shouldn't be
> using the embedding area because it was never defined to be used for
> anything in particular and has no protocol for arbitrating among
> conflicts like this.

A valid point. All participants invite trouble.


>  but grub-devel is not a filesystem
>  development list and there's only so much we can fix).

Maybe one should use external boot media of
which GRUB can claim complete ownership.
I.e. an USB stick or a CD which hosts GRUB and
a custom configuration.
This way, GRUB would have no shares in the
embattled area at all.

Main development task would be to allow
easy creation and manipulation of the boot
media. As frontend of grub-mkrescue ?

Would ISO 9660 multi-session be suitable for
changing GRUB configuration on CD ?
A new session would be added with a new set
of volume descriptors (superblock) and a new
directory tree. Plus new or changed files.
Does GRUB know it has to "mount" the first
track of the last session on CD/DVD/BD media ?
(I assume it knows when it deals with MMC
 media.)


> We won't do ourselves
> any favours by appearing to be a poor citizen.

How about GRUB offers to become the umpire
of the playfield ?

I.e. to have on the external media:
- GRUB
- copies of the MBR and embedded area
  of each involved operating system
- a feature which puts one of those copies onto
  hard disk according to menu choice of the
  user and then boots the copied MBR.
- a feature which copies found MBR and embedded
  area onto external media or remote systems.

I am not educated enough to know whether GRUB
already allows to copy data from its boot media
to disks.

Actually i have a gzpLinux CD with custom SSH
setup which allows me to boot my test machine
and to restore backups of MBR + "embedded area"
remotely from my workstation.
This allowed me to switch between GRUB and boot
loaders of FreeBSD and OpenSolaris before i found
out how to make GRUB boot those other systems.
(My GRUB is hosted by a Debian system.)

To have a complete GNU/Linux as umpire is
appealing to me. So eventually GRUB development
should consider to adopt an existing rescue
system for that purpose.
This system could then update its own GRUB
configuration. (It would be interesting to make
it add a new session to its own boot CD :)).


Have a nice day :)

Thomas