I just took care of making that fatal error a warning instead.
Will be fixed with upcoming release of grml2usb.

Thanks for reporting!

regards,
Mika

Hi,

sorry for the long delay in getting back to your bug report :(

* ddio wrote in grml's BTS on 20150522 / 19:51:

> I wanted to install grml on a live stick with logical partitions, but got the 
> error:

> Fatal: installation on partition number >4 not supported. (BIOS won't support 
> it.)

> But as I bootet from an logical partition 5mins before I couldn't believe thats 
> true, so I simple commented out these lines:

> 1808         if not os.path.isdir(device):
> 1809             if device[-1:].isdigit():
> 1810                 if int(device[-1:]) > 4 or device[-2:].isdigit():
> 1811                     logging.critical("Fatal: installation on partition 
> number >4 not supported. (BIOS won't support it.)")
> 1812                     sys.exit(1)

> and tried, and it worked! I don't know if it works on all modern Boards or only 
> on some, or whatever. I have an Asrock Z77 Pro4 with P1.80...

> So it's definitely not always right!

Indeed, it's quite system dependent and possibly not even true by
default for the typical system nowadays. Since it's quite annoying
to end up with a non-bootable system though it still might be better
to be safe than sorry. Though we should adjust our error message and
support skipping this check.

Thanks for your bug report!

regards,
-mika-

Hi,

I wanted to install grml on a live stick with logical partitions, but got the 
error:

Fatal: installation on partition number >4 not supported. (BIOS won't support 
it.)

But as I bootet from an logical partition 5mins before I couldn't believe thats 
true, so I simple commented out these lines:

1808         if not os.path.isdir(device):
1809             if device[-1:].isdigit():
1810                 if int(device[-1:]) > 4 or device[-2:].isdigit():
1811                     logging.critical("Fatal: installation on partition 
number >4 not supported. (BIOS won't support it.)")
1812                     sys.exit(1)

and tried, and it worked! I don't know if it works on all modern Boards or only 
on some, or whatever. I have an Asrock Z77 Pro4 with P1.80...

So it's definitely not always right!