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boot to extended partition?

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Thread Starter 
If i have an os, can i shrink it, then use the extended partition to run a second os?

basically can i boot to an extended partition?
post #2 of 2
Quote:
Originally Posted by hoth17 View Post
If i have an os, can i shrink it, then use the extended partition to run a second os?

basically can i boot to an extended partition?
yes, you can.

If you are starting from scratch:

Create a small primary partition, flag it as 'boot' partition and boot all your OSes from there. You will of course need to write (fixboot) the correct boot sector and have minimal system files like NTLDR in that partition and list your OSes in boot.ini. The disks in boot.ini start with 0. Look at existing boot.ini from an XP system.

The trick lies in the fact that each OS should see the partition that they are on as C:. You can use something like grub's hide and map commands to achieve that.

An example 32 and 64 bit XP dual boot using grub is like:
Code:
title=Microsoft XP Pro x32
        unhide (hd0,0)
        hide (hd0,1)
        rootnoverify (hd0,0)
        makeactive
        chainloader (hd0,0)+1
        boot

title=Microsoft XP Pro x64
        hide (hd0,0)
        unhide (hd0,1)
        rootnoverify (hd0,1)
        makeactive
        chainloader (hd0,1)+1
        boot
hd0,0 contains 32-bit XP. hd0,1 contains the small boot partition with boot.ini having reference to hd0,6 which contains my 64 bit OS.

So, when I select "Microsoft XP Pro x32" from grub menu, I get boot.ini from hd0,0 and when I select "Microsoft XP Pro x64", I get boot.ini from hd0,1.

Notice how hide (hd0,0) hides 32-bit XP from 64 bit XP.

The above is good when you are doing a fresh start.

But in your case, since the second OS will write a new MBR to disk, you will need to list the first OS in the boot.ini of the second OS.

If you get into trouble with drive letters, install grub4dos and follow the above method to salvage your OSes. You will need to fixboot each OS separately on their respective partitions and install grub4dos on the MBR.

And lastly, make a backup before starting on this journey....
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Predator
(13 items)
 
  
CPUMotherboardGraphicsRAM
i7 920 D0@4.4Ghz with 1.3125v, w3520 D0 @ 4.4Ghz EVGA X58 SLI GT9600 6x2GB OCZ Gold 1600MHz 
Hard DriveOSMonitorPower
120G Vertex, 256GB M4, 3xSeagates on LSI 9211-8i Linux amd64, XP64 Dell 24" Antec 850 TP Quattro 
Case
Thermatake Xaser VI 
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