GRUB error -- dual booting Linux and WinXP

anomie · 10-08-2005, 11:21 PM

Quote:

I keep getting "Error 21: selected disk does not exist" when I try to boot as WindowsXP
and then it says push any key to continue...and I'm returned to initial grub boot-up page (where I choose which OS I want to run). Intuition tells me that this problem is some sort of newbie-like error that I'm overlooking...

Your ubuntu installer was smart enough to try the map/map trick, but it does not always work. The problem is Windows throws a fit if it is not on the first physical drive in the system.

Back up your menu.lst, and try these changes to the Windows entry:

Code:

title Microsoft Windows XP Professional
map (hd0) (hd1)
map (hd1) (hd0)
rootnoverify	(hd0,0)
makeactive
chainloader +1

Have a look at the manual if you want to read more on this problem: http://www.gnu.org/software/grub/man...2fWindows.html

j3nnifers · 10-09-2005, 07:25 AM

chazoroch · 10-22-2005, 09:17 AM

I recently solved a similar problem (about 1 hour ago).
Windows and Linux were separately installed on two different drives.
So both OS(s) thought they were on the master drive.

There is a small difference in the GRUB config for my Windows selection:

title Windows XP (On Slave)
rootnoverify (hd1,0)
# begin magic
map (hd0) (hd1)
map (hd1) (hd0)
# end magic
makeactive
chainloader +1

The hardware configuration is Linux on the primary master and Windows on the primary slave.
In the config above "rootnoverify (hd1,0)" is done first and references the Windows slave drive.
The "magic" section then remaps the slave to the master which probably keeps Windows happy.
"makeactive" probably has no effect. There is no reference to a drive in the 'chainloader".

I spent part of last week trying different approaches. My original Linux install wiped out my Windows drive which is why I installed them separately with only 1 of the 2 drives in my machine at a time. And then when I put the two together that was when the fun began. Several posts talked about creating a Linux.bin from the Linux /boot drive, tried it, it didn't work. And others talked about installing GRUB on the Windows drive which I thought might corrupt the MBR and the ntldr would no longer work which would wipe out the drive again.

Anyways the Windows drive is completely portable, it could be installed in a fresh computer and work. And I refused to put the GRUB or any part of Linux on the drive due to Linux install wiping it out previously.

The bottom line is the map "magic" fools Windows into thinking it's the master, the ntldr executes and it works!

rbad · 06-27-2006, 03:13 PM

Quote:

Originally Posted by chazoroch

I recently solved a similar problem (about 1 hour ago).
Windows and Linux were separately installed on two different drives.
So both OS(s) thought they were on the master drive.

There is a small difference in the GRUB config for my Windows selection:

title Windows XP (On Slave)
rootnoverify (hd1,0)
# begin magic
map (hd0) (hd1)
map (hd1) (hd0)
# end magic
makeactive
chainloader +1

The hardware configuration is Linux on the primary master and Windows on the primary slave.
In the config above "rootnoverify (hd1,0)" is done first and references the Windows slave drive.
The "magic" section then remaps the slave to the master which probably keeps Windows happy.
"makeactive" probably has no effect. There is no reference to a drive in the 'chainloader".

I spent part of last week trying different approaches. My original Linux install wiped out my Windows drive which is why I installed them separately with only 1 of the 2 drives in my machine at a time. And then when I put the two together that was when the fun began. Several posts talked about creating a Linux.bin from the Linux /boot drive, tried it, it didn't work. And others talked about installing GRUB on the Windows drive which I thought might corrupt the MBR and the ntldr would no longer work which would wipe out the drive again.

Anyways the Windows drive is completely portable, it could be installed in a fresh computer and work. And I refused to put the GRUB or any part of Linux on the drive due to Linux install wiping it out previously.

The bottom line is the map "magic" fools Windows into thinking it's the master, the ntldr executes and it works!

I too had the same problem. However i did'nt solve it by adding the #magic line. The issue was solve with...

title Microsoft Windows XP Professional
map (hd0) (hd1)
map (hd1) (hd0)
rootnoverify (hd0,0)
makeactive
chainloader (hd1,0)+1

The change being "chainloader (hd1,0)+1"
Seems to work fine now.