Re: Can Grub start Windows XP from "other" partition

[Felix Miata]

On 2012-11-22 03:36 (GMT+0100) Ulf Zibis composed:

> > Grub Legacy can do the very same partition type modifications at boot time. I 
> > doubt this
> > capability has been dropped from Grub2. I don't use Grub2, and install no 
> > bootloader during
> > installation of non-*buntu distros that do not offer to install Grub Legacy.

> Can you point me to the paragraph in Grub Legacy docs, where this is described? 
> This would ease me
> to possibly find that feature in Grub 2.

http://orgs.man.ac.uk/documentation/grub/grub_4.html#SEC22

> > > I remember that I had read a tutorial about "duplicating Windows" to 2 
> > > partitions for the purpose to
> > > have a working installation and a test installation to try out dangerous things 
> > > without corrupting
> > > the first. I'm pretty sure, that the 2nd one was created by just copying the 
> > > 1st, and if booted into
> > > the 2nd, partition 1 appeared as D:.
> > > Unfortunately I do not find this tutorial again by Google.

> Do you have an idea, how this could have been possible, or do you know about a 
> doc which may help me?

Maybe it could be done with XXCOPY while booted to a maintenance system, but 
not by a partition clone. Registry modifications would be required as well as 
adjusting boot.ini.

One reason cloning cannot be expected to work can be seen by a study of 
http://fm.no-ip.com/Tmp/Dfsee/dfsw5000.txt

Notice that the three primary partitions seem to be equal in size, except 
that they are not. The first is smaller by the number of sectors in a track 
minus one. To try to clone between a first and an other would cause sector 
counts to be out of sync with "cylinder" alignment, something Linux can cope 
with, but WinXP can't.

> > > > Windows needs a primary to be C:, but it needn't be "installed" to C:.

> > > In other words, Windows needs the NTloader, boot.ini etc. in the first 
> > > Windows-visible-native-typed
> > > partition which is always named as C:. If Windows itself is "installed" in any 
> > > other other
> > > partition, it would be named different, e.g. D:, E: ... right?

> > Yes.

> But how does it work, if there are 2 Windows installations with 2 NTloaders?

Proper configuration of menu.lst, including hiding and unhiding of primaries.

> If Windows can only be booted by the NTloader from the 1st partition,

Where did you get this idea? WinXP can only be booted from an only visible 
primary.

> how can Grub tell it to boot the Windows installation from the 2nd partition?

Windows can be booted by any primary partition that contains NTLDR, if it is 
an unhidden partition, and there no other Windows native unhidden primary 
partitions.

> But if there are 2 Windows installations on a system, both listed in Grub's 
> start menu, each has
> it's own NTLDR + boot.ini with only 1 default entry, how can Grub manage to 
> chainload the right
> NTLDR, or instruct the NTLDR in the 1st partition to boot the Windows 
> installation in the 2nd partition?

Can't do that. Once chainloaded, you have to use the Windows boot menu from a 
properly constructed boot.ini. This will be necessary if you make only one 
primary to be used as C:. You only put two Windows stanzas in Grub's menu if 
you have two different primaries that could be C:.

> If I have understood right, Grub can boot Linux from any arbitrary partition, 
> but in case of Windows
> it should fallback to the BIOS which boots the Windows installation from the 
> "active" partition,
> which can only be one of the two.

You don't have it right.

> Or ist it like this? :
> Grub can start *any* NTLDR regardless of the "activeness" of it's enclosing 
> partition.

"Active" is only relevant with regard to MBR code. It indicates the jumpto 
partition. With Grub on a primary and standard code in the MBR, active must 
be and remain the primary that Grub is on, unless you wish Grub to be a 
secondary boot loader chainloaded from elsewhere, such as via boot.ini on a C:.

> In case of the NTLDR of the 2nd Windows-visible-native-typed partition it will 
> boot the 2nd Windows partition,
> but "see" the 1st Windows partition as C: and the 2nd as D:, which is the big 
> problem here if it was
> originally installed on C:

Windows cannot boot a system with more than one visible native type primary 
per HD. In a single HD system, D: will always be a logical, and C: will be 
the one and only visible primary.
--
"The wise are known for their understanding, and pleasant
words are persuasive." Proverbs 16:21 (New Living Translation)

 Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata  ***  http://fm.no-ip.com/