# grub-install : Unknown partition table signature

## eponymous

Hi guys,

Doing a: 

```
grub-install --no-floppy /dev/sda
```

on an ext4 boot partition results in a lot of "Unknown partition table signature" messages but it seems to complete and reports no errors.

If I do a manual grub install using:

```
grub> root (hd0,0)   

grub> setup (hd0) 

grub> quit
```

I don't get any errors or messages regarding the table signatres.

Is this a bug in grub?

Cheers.

----------

## NeddySeagoon

eponymous,

Its probably not a grub bug - it would be all over the forums if it were.

Be aware that (hd0) may not be /dev/sda.

(hd0) is the first drive discovered by the BIOS.  /dev/sda is the first drive discovered by the kernel.

If you have more than one drive these need not be the same drive.

Some braindead BIOS's report the boot drive as (hd0), regardless of which drive it actually is, in which case, with 2 or more drives installed you may encounter the above BIOS 'feature'.

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## eponymous

 *NeddySeagoon wrote:*   

> eponymous,
> 
> Its probably not a grub bug - it would be all over the forums if it were.
> 
> Be aware that (hd0) may not be /dev/sda.
> ...

 

The thing is, I'm booting into my Gentoo install just fine :S

Is there any way to check which device hd0 actually is?

* UPDATE: Oh now this is really odd. I've just tried doing the exact same thing again (after making a tweak to my grub.conf to add a rootfs=ext4 line) and it worked fine without any error messages :S

I'm confused.

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## NeddySeagoon

eponymous,

That makes no sense.  A grub doesn't care what your kernel root file system is unless /boot is not a real partition, then it has to read files from your kernel root.  In any case, rootfs= is a kernel parameter.

"Unknown partition table signature" refers to the last two bytes in the MBR, which must be 0x0aa 0x55.  Don't quote me on the order.

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## eponymous

 *NeddySeagoon wrote:*   

> eponymous,
> 
> That makes no sense.  A grub doesn't care what your kernel root file system is unless /boot is not a real partition, then it has to read files from your kernel root.  In any case, rootfs= is a kernel parameter.
> 
> "Unknown partition table signature" refers to the last two bytes in the MBR, which must be 0x0aa 0x55.  Don't quote me on the order.

 

Hi Neddy, sorry that is misleading. I didn't mean to imply that adding rootfs=ext4 solved the problem - I was merely stating what I had changed (to fix another problem) before I did another grub-install.

----------

