Stupid dual boot question

sumguy231 · 03-14-2005, 07:30 PM

I know this is a pretty stupid question, and even though I have been using Linux for a little while, I haven't had to deal with this before.
I have on my primary hard drive Windows at hda1, and Linux at hda2. I've installed GRUB, and read a few tutorials on dual booting. The official documentation states that since Windows is an unsupported OS, it uses the 'chainloader' command to pass the booting over to the Windows bootloader. What I'm wondering about is, with my current setup is this possible? I thought that when one bootloader(GRUB) was written to the MBR, then the other bootloader(NTLDR?) was overwritten. I'm embarrased and clueless about this.

Can anybody answer this for me?

syg00 · 03-14-2005, 09:17 PM

Terminolgy problem.
The boot record is overlaid - in this case by grub, which is capable of multi loading.
Consider the code in the boot record (usually called the MBR) as phase 1 of the boot loader. Because of the restricted real estate available (446 bytes maximum), there's only a limited amount it can do.
The real work is done by code in a partiton - ntldr for XP, and the stage files for grub.
That is the real "boot-loader" code.

"Unsupported" in this case probably means "not multiboot capable". Grub provides all that functionality, and "chainloads" the XP partition boot sector record, and transfers control. At that point, the XP boot-loader in not even aware that it wasn't directly loaded by it's own (brain-dead) boot record in the MBR.

sumguy231 · 03-15-2005, 05:45 PM

Sorry about this, just checking, would this be correct in most cases?

Code:

title Windows
unhide (hd0,0)
rootnoverify (hd0,0)
makeactive
chainloader +1
boot

soulstace · 03-15-2005, 07:51 PM

here is grub.conf code to boot windows. very simple.

Code:

title Windows
        rootnoverify (hd0,0)
        chainloader +1