> Re: New Idea - can GRUB also write on file systems ?
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> * From: OKUJI Yoshinori
> * Subject: Re: New Idea - can GRUB also write on file systems ?
> * Date: Fri, 14 Apr 2000 00:44:47 -0700
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>
> That is not a new idea. Several persons have requested the feature,
> but I'm not enthusiastic with that, since that's difficult. Writing a
> file or directory to a filesystem is much more complicated than
> reading a file or directory from a filesystem. And, of course, it will
> bring up many security-related issues. We will also have to ensure
> that it is enough robust. Then, must we give the user fsck and/or
> defrag? All of these seems like a nightmare.
>
> Okuji
>
You are right, this is a big problem.
The only way to do this, is to overthink, if there is a really need
for that. And there is only one case often found in the embedded world,
where this feature really help, in all other cases the use of an OS
is the better way of writing disks.
Now to this special case:
There are several embedded cpu boards on the market, haveing a big
bios flash (1MB up to 4MB), where the unused part is used as bios
supported disk. (For example: Jumptec MOPS/586 has a 1.6MB flash
harddisk, typically used for a embedded or normal DOS with FAT
on it).
I have also disk machine, and of course I installed a DOS (only
partially) on this disk + plus software for configuring the ethernet
controller etc. (I don't like DOS really, but in some cases ....)
I also installed GRUB on it !!!
On this machine it is not possible to install a betboot ROM, so the
solution is to install GRUB on this 'BIOS-DISK' and
* new feature *
and load the 'menu.lst' from server (via bootp).
(The new feature is, that GRUB should be able to load 'menu.lst'
from the net, although we have booted local. This could be implemented
with another option, like --menu-remote. This would add the diskless
stuff, but not produce a netbootable image).
The problem with this 'disk' is, that the method reprogramming it
is not documented and the disk can only be used in real-mode under
bios control (described in the manual of the board). So I have to
boot DOS to update for example 'stage2', has to boot GRUB from floppy,
because the block list is invalid then, and install GRUB with 'setup'.
The second problem is to have a useful TCP/IP connection with a DOS
machine, installed on a 1.6MB disk. So I have to play "floppy-net".
This is true for many embedded machines and also for CPU modules like
"phytec" products, etc.
So the possibility is to support the diskwriting only for that kind
of use:
DOS-FAT and disk under bios control.
With friendly regards
Christoph Plattner
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