How do I add Windows 7 to GRUB 2?

Question

I am having trouble adding Windows 7 to my GRUB 2 boot menu. I know similar questions have been asked and answered on this site and others, but none of the answers seem to work for me.

My setup: Two hard drives, sda with a Win 7 installation and sdb with a Debian installation and GRUB2.

In my BIOS, I can choose which hard drive to boot from, and if I boot from the first hard drive Windows starts so I know that it is working. Now I want to add a menu item to GRUB to boot Windows.

I downloaded bootinfoscript and ran it, here is the RESULTS.txt:

                  Boot Info Script 0.61      [1 April 2012]


============================= Boot Info Summary: ===============================

 => Windows is installed in the MBR of /dev/sda.
 => Grub2 (v1.99) is installed in the MBR of /dev/sdb and looks at sector 2048 
    of the same hard drive for core.img. core.img is at this location and 
    looks for (,gpt2)/boot/grub on this drive.

sda1: __________________________________________________________________________

    File system:       
    Boot sector type:  Windows Vista/7: NTFS
    Boot sector info: 
    Mounting failed:   mount: unknown filesystem type ''

sda2: __________________________________________________________________________

    File system:       ntfs
    Boot sector type:  Windows Vista/7: NTFS
    Boot sector info:  No errors found in the Boot Parameter Block.
    Operating System:  Windows 7
    Boot files:        /Windows/System32/winload.exe

sdb1: __________________________________________________________________________

    File system:       BIOS Boot partition
    Boot sector type:  Grub2's core.img
    Boot sector info: 

sdb2: __________________________________________________________________________

    File system:       ext4
    Boot sector type:  -
    Boot sector info: 
    Mounting failed:   mount: unknown filesystem type ''
mount: /dev/sdb2 already mounted or sdb2 busy

sdb3: __________________________________________________________________________

    File system:       swap
    Boot sector type:  -
    Boot sector info: 

============================ Drive/Partition Info: =============================

Drive: sda _____________________________________________________________________

Disk /dev/sda: 256.1 GB, 256060514304 bytes
255 heads, 63 sectors/track, 31130 cylinders, total 500118192 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

Partition  Boot  Start Sector    End Sector  # of Sectors  Id System

/dev/sda1    *          2,048       206,847       204,800   7 NTFS / exFAT / HPFS
/dev/sda2             206,848   500,115,455   499,908,608   7 NTFS / exFAT / HPFS


Drive: sdb _____________________________________________________________________

Disk /dev/sdb: 3000.6 GB, 3000592982016 bytes
255 heads, 63 sectors/track, 364801 cylinders, total 5860533168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes

Partition  Boot  Start Sector    End Sector  # of Sectors  Id System

/dev/sdb1                   1 4,294,967,295 4,294,967,295  ee GPT


GUID Partition Table detected.

Partition    Start Sector    End Sector  # of Sectors System
/dev/sdb1           2,048         4,095         2,048 BIOS Boot partition
/dev/sdb2           4,096 2,605,768,703 2,605,764,608 Data partition (Windows/Linux)
/dev/sdb3   2,605,768,704 2,639,306,751    33,538,048 Swap partition (Linux)

"blkid" output: ________________________________________________________________

Device           UUID                                   TYPE       LABEL

/dev/sda2        DCA04533A0451584                       ntfs       
/dev/sdb2        ea61c63c-0a93-44fb-894c-f652c28b67d0   ext4       
/dev/sdb3        ca9c61ec-f99e-428c-bdf3-65fbbfc4b43b   swap       

================================ Mount points: =================================

Device           Mount_Point              Type       Options

/dev/disk/by-uuid/ea61c63c-0a93-44fb-894c-f652c28b67d0 /                        ext4       (rw,relatime,errors=remount-ro,user_xattr,barrier=1,data=ordered)
/dev/sda2        /mnt/win                 fuseblk    (ro,nosuid,nodev,noexec,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096)


=============================== StdErr Messages: ===============================

xz: (stdin): Compressed data is corrupt

OS-prober does not seem to be able to detect my Win7 installation. If I run update-grub2 (which I believe in turn runs OS-prober) it will output:

Generating grub.cfg ...
Found background image: /usr/share/images/desktop-base/desktop-grub.png
Found linux image: /boot/vmlinuz-3.2.0-4-amd64
Found initrd image: /boot/initrd.img-3.2.0-4-amd64
done

I have tried some variations on GRUB menu entries (by modifying /etc/grub.d/40_custom and then running update-grub2). Here are some of them:

The first one is simple, inspired by (for instance) this link: http://technologytales.com/2010/11/21/manually-adding-an-entry-for-windows-7-to-an-ubuntu-grub2-menu/

menuentry 'Windows 7' {
set root='(hd0,2)'
chainloader +1
}

This will not boot, and results in the following output from GRUB:

  Booting a command list

error: invalid signature.

Press any key to continue...

Then I tried this:

menuentry 'Windows 7' --class windows --class os {
insmod part_msdos
insmod ntfs
set root='(hd0,2)'
search --no-floppy --fs-uuid --set=root DCA04533A0451584
chainloader +1
}

which results in:

BOOTMGR is missing
Press Ctrl+Alt+Del to restart

and then I tried:

menuentry 'Windows 7' --class windows --class os {
insmod part_msdos
insmod ntfs
insmod ntldr
set root='(hd0,2)'
search --no-floppy --fs-uuid --set=root DCA04533A0451584
ntldr ($root)/Windows/System32/winload.exe
}

which does not work either (goes to an empty screen with a blinking cursor).

I am really at a loss here. Any help would be greatly appreciated!

Update: I ran boot-repair-disk (as suggested by moses in comments) with default settings. It did not add a Win7 entry to the boot menu. Maybe it failed to detect the Win7 installation since it overwrote its MBR with GRUB. Here is a link to the boot-repair-disk log.

Solution

The problem is that Windows 7 uses a 100MB system partition which holds the boot files. So you need to boot from it, not your Windows drive(which is called the boot partition).

menuentry 'Windows 7' {
set root='(hd0,0)'
chainloader +1
}

Note GRUB counts partitions from 0, so /dev/sda1 is (hd0,0), /dev/sda2 is (hd0,1). Although, there seems to be a problem with boot info script saying it can't mount the filesystem, this will most likely work.

Comments

[Admin]

Have you tried simply running the automatic Boot-repair-disk? It scans all operating systems and rebuilds grub without the need to manually do it.

[user829876]

Thanks for the tip! I didn't know boot-repair-disk existed. I ran it with default settings but did not add any entry to GRUB's menu. Updating the question above with boot-repair log.