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I am trying to be able to boot into windows from grub. If I select the windows hdd from the bios boot options, I can get in no problem, so the windows bootloader seems to still be intact. I have tried the following in /etc/grub/40_custom (followed by update-grub):

menuentry "Windows 7 (loader)" {
    set root=(hd0,1)
    chainloader +1

I have tried multiple combinations of set root=(hdx, y) but I keep getting errors along the lines of 'the partition doesn't exist.

fdisk -l results are:

   Device Boot      Start         End             Blocks       Id      System
/dev/sda1   *        2048      206847         102400       7  HPFS/NTFS/exFAT
/dev/sda2          206848   175833087    87813120    7  HPFS/NTFS/exFA

I don't know if this is related, but I am also running into some strangeness that I have never seen before. I have linux and grub installed on one disk (encrypted lvm) and windows installed on a separate disk. If I unplug my windows disk, so that the linux disk is the only thing plugged into the system, and then go to the boot order from the bios, I see the disk name, as well as a separate bootable option called 'debian'. If I try to boot from the disk it complains about grub not working (will update with exact error), but if I try to boot from the debian option then I get my grub, and can get into the linux os no problem. If I unplug the linux hdd, that debian option disappears from the boot menu. What would cause that, and could it be related?

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migrated from serverfault.com Jul 20 '13 at 2:33

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