Latest LQ Deal: Linux Power User Bundle
Go Back > Forums > Linux Forums > Linux - Newbie
User Name
Linux - Newbie This Linux forum is for members that are new to Linux.
Just starting out and have a question? If it is not in the man pages or the how-to's this is the place!


  Search this Thread
Old 04-27-2009, 11:38 AM   #1
Registered: Jul 2008
Location: Chennai, India
Distribution: RHEL5, Ubuntu
Posts: 191

Rep: Reputation: 37
A question on GRUB and NTLDR

Hello Friends..

My question is as follows:

Once we install XP, ntldr will be occupying the MBR. But later if we install Linux (dual booting), GRUB (stage I) will be occupying the MBR. My doubt here is, to which location the ntldr will be placed?. Will GRUB put the ntldr to a windows partition and then later will chainload the ntldr from the Windows partition to RAM when the user selects the XP operating system from the Boot menu?....
I can understand the chainloading concept (a bootloader loading another bootloader), but what i wish to know is, is the ntldr is taken off the MBR and placed to a different place when GRUB is placed in MBR?

please pardon if my concept is wrong. Thank you.
Old 04-27-2009, 12:17 PM   #2
LQ Guru
Registered: Apr 2008
Distribution: PCLinux, Slackware
Posts: 7,267

Rep: Reputation: 1370Reputation: 1370Reputation: 1370Reputation: 1370Reputation: 1370Reputation: 1370Reputation: 1370Reputation: 1370Reputation: 1370Reputation: 1370
The stage1 file of Grub is placed in the mbr in your scenario but all of the Grub bootloader files are not, obviously since the mbr is only 512 bytes. Grub doesn't place ntldr anywhere, it is installed to the root of the windows partition (usually C:\). Not using windows I'm not sure what file xp puts in the mbr. In my W98 install it was a file called bootsect.dos, which is 512 bytes just like stage1 in Grub.

Grub basically just points to where the windows bootloader is (or should be) on the windows partition.
Old 04-27-2009, 02:55 PM   #3
LQ Veteran
Registered: Nov 2005
Location: Annapolis, MD
Distribution: Arch/XFCE
Posts: 17,802

Rep: Reputation: 738Reputation: 738Reputation: 738Reputation: 738Reputation: 738Reputation: 738Reputation: 738
Yes, NTLDR is the name for what Windows uses after the initial boot code. I suppose it is analogous to something like GRUB stage 1.5 or 2.

Windows puts boot code in the MBR which is analogous to GRUB stage 1.
Old 04-27-2009, 07:18 PM   #4
LQ Guru
Registered: Feb 2004
Location: SE Tennessee, USA
Distribution: Gentoo, LFS
Posts: 8,208
Blog Entries: 4

Rep: Reputation: 2764Reputation: 2764Reputation: 2764Reputation: 2764Reputation: 2764Reputation: 2764Reputation: 2764Reputation: 2764Reputation: 2764Reputation: 2764Reputation: 2764
The documentation for Grub is actually quite extensive about just how it is able to boot Windows. (This is not an "RTFM" response!)

When you boot NT natively:
  • The MBR passes control to NTLDR.
  • NTLDR boots the system.

Basically, when you're using Grub:
  • The MBR passes control to Grub.
  • You choose to boot Windows.
  • Grub hands-off control to NTLDR in exactly the same way that the MBR would have done.
  • Your computer hardware whines because you are once again forcing it to endure Windows instead of a nice, civilized operating system like Linux.
  • NTLDR boots the system.
Old 04-27-2009, 07:25 PM   #5
Registered: Sep 2006
Location: Canada
Distribution: Gentoo
Posts: 702

Rep: Reputation: 43
As per Wikipedia:

The conventional MBR code expects the MBR Partition Table scheme to have been used, and scans the list of (primary) partition entries in its embedded partition table to find the only one that is marked with the active flag. It then loads and runs the Volume Boot Record for that partition.
Old 04-27-2009, 09:46 PM   #6
Registered: Jul 2008
Location: Chennai, India
Distribution: RHEL5, Ubuntu
Posts: 191

Original Poster
Rep: Reputation: 37
Thank you friends for all your responses. Let me type what I understood:

NTLDR will be installed not in the MBR, but in the active partition of Windows and the partitition table entry with the active flag set will be used for booting and that is where ntldr is stored.
Is it right?


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
'NTLDR missing' booting XP with grub galle Linux - Software 11 12-23-2009 05:52 PM
GRUB NTLDR Missing?? CuriousCat Mandriva 3 03-29-2009 12:32 PM
grub & ntldr conrad987 Linux - Software 1 03-08-2005 03:40 PM
GRUB: NTLDR not found. Or is it? JZL240I-U Linux - Software 2 03-07-2005 03:33 AM
re-installed GRUB now NTLDR is missing Sygnus X1 Linux - Newbie 8 01-15-2005 01:07 PM

All times are GMT -5. The time now is 02:47 PM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration