Re: "Unknown partition table signature" when installing GRUB onto EXT2 floppy

[Ersin Akinci]

Fascinating!  That worked perfectly.  I swear that I had basically
tried the same thing with the loop device, but I must mistyped
something.  Thanks very much for the advice (and the explanation),
everything's in working order...well, except for the fact that my
floppy isn't loading my kernel now, but that's a different problem
altogether =).

-Ersin

On Wed, Sep 23, 2009 at 4:16 PM, Michael Evans <address@hidden> wrote:
> I created a 1440KB image and forced mkfs.ext2 to run on it.  This is top of
> the hexdump for that file.
>
> 00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
> |................|
> *
> 00000400  b8 00 00 00 a0 05 00 00  48 00 00 00 71 05 00 00
> |........H...q...|
> 00000410  ad 00 00 00 01 00 00 00  00 00 00 00 00 00 00 00
> |................|
>
> You might note how only 1kb of free space remains at the start of the file
> (device)?  That is not enough space for a stage 1.5 image.  However you
> should probably be able to force a stage 1 install by manually using an
> invocation including this:
>
> For me the first works:
> grub --device-map=/media/vfloppy/grub/device.map
> Unknown partition table signature
>
>        [ Minimal BASH-like line editing is supported.   For
>          the   first   word,  TAB  lists  possible  command
>          completions.  Anywhere else TAB lists the possible
>          completions of a device/filename. ]
> grub> root (fd0)
> root (fd0)
> grub> setup (fd0)
> setup (fd0)
>  Checking if "/boot/grub/stage1" exists... yes
>  Checking if "/boot/grub/stage2" exists... yes
>  Checking if "/boot/grub/e2fs_stage1_5" exists... yes
>  Running "embed /boot/grub/e2fs_stage1_5 (fd0)"... failed (this is not
> fatal)
>  Running "embed /boot/grub/e2fs_stage1_5 (fd0)"... failed (this is not
> fatal)
>  Running "install /boot/grub/stage1 (fd0) /boot/grub/stage2 p
> /boot/grub/menu.lst "... succeeded
> Done.
> grub>
>
> NOTE:
> 1) The virtual floppy is mounted.
> 2) The virtual floppy contains stage1 and stage2 inside of grub/
> 3) The virtual floppy has a symlink 'boot' which points to .  (e.g. cd
> /media/vfloppy ; ln -s . boot )
> 4) I have prepared a device.map file and provided it to the grub shell to
> tell grub that at boot time 'fd0' will actually match the loopback adapter
> currently in use.
>
> === Contents of device.map ===
> (fd0)   /dev/loop0
>
>
> The Install command can also be invoked manually, you should give it a good
> reading to understand what the last step above accomplished.
> http://www.gnu.org/software/grub/manual/html_node/install.html#install
>
> On Wed, Sep 23, 2009 at 12:46 PM, Ersin Akinci <address@hidden>
> wrote:
>>
>> Hi all,
>>
>> I'm not sure if this is a bug or if what I'm trying to do is simply
>> unsupported, but I'm trying to install GRUB (0.97) onto a floppy
>> formatted as ext2 and I keep getting the error "unknown partition
>> table signature".  Here's what I've been doing:
>>
>> $ mke2fs /dev/fd0
>> $ mount /dev/fd0
>> $ mkdir -p /media/floppy/boot/grub
>> $ cp /boot/grub/stage* /media/floppy/boot/grub
>> $ umount /dev/fd0
>>
>> Then, at the GRUB prompt:
>>
>> grub> root (fd0)
>> Unknown partition table signature
>>
>> Trying to do setup (fd0) after that also results in an error.  My
>> media is not the problem, because I've also tried doing the same thing
>> using a disk image mounted as a loopback device, which still gives the
>> same error.  Looking around on the Internet, it seems like this is a
>> common problem, but no one has a solution.
>>
>> Also, I can't use the instructions at
>>
>> http://www.gnu.org/software/grub/manual/html_node/Creating-a-GRUB-boot-floppy.html
>> (which tell the user to dd stage1 and stage2 to the beginning sectors
>> of the floppy) because I need to use the rest of the disk.
>>
>> I take it that floppies aren't meant to have partition tables and
>> partitions like hard drives...?  But then what is GRUB complaining
>> about...
>>
>> Any ideas?
>>
>> -Ersin
>>
>>
>> _______________________________________________
>> Help-grub mailing list
>> address@hidden
>> http://lists.gnu.org/mailman/listinfo/help-grub
>
>



-- 

=========

Ersin Y. Akinci -- http://www.ersinakinci.com