grub: windows on logical partition

festhead · 12-16-2007, 08:48 AM

hi,

how do I boot into windows with grub?
my windows is installed on hda7, which is a part of hda4 (logical partition)

i (re-) installed windows after linux (i know...), and fixed the mbr already, but the new windows is not accessable

thx!

TSquaredF · 12-16-2007, 08:56 AM

Hello, festhead.
I won't claim to be an expert on this, because I normally install windows in hda1, as recommended. That said, however, you can remap partitions in GRUB (read 'info grub') to make windows think it is running on the first partition.
Regards,
Bill

David1357 · 12-16-2007, 10:23 AM

Quote:

Originally Posted by festhead

how do I boot into windows with grub?
my windows is installed on hda7, which is a part of hda4 (logical partition)

Before you do what I describe below, copy "/boot/grub/menu.lst" to "/boot/grub/menu.lst.good" or the equivalent.

My Windows entry in "/boot/grub/menu.lst" looks like this:

Code:

title           Microsoft Windows XP Home Edition
root            (hd0,0)
savedefault
makeactive
chainloader     +1

If you change (hd0,0) to (hd0,7), you will be able to boot Windows. You might have to toggle the "bootable" flag using fdisk.

syg00 · 12-16-2007, 12:22 PM

Ain't gunna work.
Even though you installed Windoze to a logical partition, the actual loader code (ntldr, boot.ini) has to be in a primary partition.
That's what you need to chainload to.

David1357 · 12-17-2007, 08:21 AM

Quote:

Originally Posted by syg00

Even though you installed Windoze to a logical partition, the actual loader code (ntldr, boot.ini) has to be in a primary partition.
That's what you need to chainload to.

I forgot about needing to change the "boot.ini" file. Your "boot.ini" will look like this:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Windows XP Home" /noexecute=optin /fastdetect

You need to change the "partition(X)" to "partition(7)". I have never heard of this "primary" partition restriction.

David1357 · 12-17-2007, 04:17 PM

Quote:

Originally Posted by syg00

Ain't gunna work.
Even though you installed Windoze to a logical partition, the actual loader code (ntldr, boot.ini) has to be in a primary partition.
That's what you need to chainload to.

If I read the GRUB manual correctly, you set the current root device to hda7 with the "root (hd0,7)" line. The Windows bootloader is in the first sector of a Windows partition. The "chainloader +1" tells GRUB to read the first sector of the current partition. As long as the "boot.ini" file is modified to use the correct partition, (e.g. multi(0)disk(0)rdisk(0)partition(7)\WINDOWS), everything should work.