Vista MBR vs. XP MBR

[CZ]

there is absolutely no doubt about that, fdisk /mbr
rewrites the disk signature, that is a long well known characteristic of
the command,

John:

Ok, I will run fdisk /mbr and post the results.

 

[Timothy Daniels]

Not true. The discussion started in the thread "Blank entries in
Boot.ini file" in microsoft.public.windowsxp.general where I
commented that there were web tutorials on restoring Vista's MBR
if it had been overwritten by an installation of XP, and you argued
that MBRs were generic.

Again, no one has said that Vista's MBR function is any different
from that of previous Windows MBRs - that is, to simply call the
executable code in the active partition's Boot Sector. The essence
of the discussion is whether *contents* of the MBRs of Vista and
previous Windows are different so as to justify reloading the Vista
MBR if it had been replaced by XP's MBR, ...OR... whether the
MBRs could be used interchangeably. So far in this discussion,
the answer appears to be "sometimes" - which implies that the
MBR recovery should be done as a standard practice unless the
user knows exactly whether some special condition existed or not.

You quoted from your source the following:

"Because you can't use the Windows XP bootloader to boot Vista,
we have to reinstate Vista's bootloader to the MBR and configure
it to manage both operating systems."

"The Windows XP bootloader gets installed to the MBR
and Vista can no longer boot." [......]


So yes, someone said something else

And you quote something which I quoted only to point out
that it is debatable (as in this thread) whether or not the MBRs
of previous Windows and Vista have the same contents and thus
whether they are interchangeable. It was never denied by anyone
posting that the MBR passes control to the Boot Sector of the active
primary partition. As it stands now, no one has shown yet one way
or the other whether the MBRs are identical or interchangeable -
especially in the general case.

*TimDaniels*

 

[CZ]

rewrites the disk signature, that is a long well known characteristic of
the command,

Ok, I will run fdisk /mbr and post the results.

John:

Ok, you are correct, Win98 SE fdisk /mbr did change the disk signature in
the MBR (sector 0).
My Vista SP1 vol has problems (is basically not useable, and is the one I
normally use for email)
My non-SP1 Vista vol works w/o problems.
I am typing this in XP Pro SP2 which works w/o problems.

However, there were some collateral issues.

I will post a more complete post when I fix the Vista SP1 vol.

PS: this computer multi-boots between several installs of Vista and XP

 

[CZ]

Ok, you are correct, Win98 SE fdisk /mbr did change the disk signature in
the MBR (sector 0).
My Vista SP1 vol has problems (is basically not useable, and is the one I
normally use for email)
My non-SP1 Vista vol works w/o problems.
I am typing this in XP Pro SP2 which works w/o problems.
However, there were some collateral issues.
I will post a more complete post when I fix the Vista SP1 vol.
PS: this computer multi-boots between several installs of Vista and XP


New comments:
The drive enumeration system was changed for the Vista SP1 vol and instead
of being C:, the vol now boots as I:.
I am surprised that it even booted.

I will have to rebuild the vol.

 

[John John]

So what is the bottom line? Is the XP MBR interchangeable with
Vista's MBR?

Interchangeable in what sense?

1- As on a Vista installation can the Vista MBR be replaced with the XP MBR?

or

2- As on a Windows XP installation can the XP MBR be replaced with the
Vista MBR?

The answers are yes, no and maybe. I'll give you my full verdict later
on. jorgen raised a point about BitLocker functions in the MBR, I'm
looking into that, it appears that the MBR must be TPM aware for
BitLocker to work properly, so if one wants to use BitLocker then other
MBR's are unsuitable.

John

 

[John John]

the MBR (sector 0).
My Vista SP1 vol has problems (is basically not useable, and is the one I
normally use for email)
My non-SP1 Vista vol works w/o problems.
I am typing this in XP Pro SP2 which works w/o problems.
However, there were some collateral issues.
I will post a more complete post when I fix the Vista SP1 vol.
PS: this computer multi-boots between several installs of Vista and XP


New comments:
The drive enumeration system was changed for the Vista SP1 vol and instead
of being C:, the vol now boots as I:.
I am surprised that it even booted.

I will have to rebuild the vol.

You could probably repair that easily by simply editing the MBR and
manually rewriting the old signature back to its location... providing
that you had saved or recorded the signature bits in case of an event
like this. You can write the signature bits back to any MBR version
that you install (W98/XP/Vista) and all your operating systems should
boot and maintain their drive letter assignement.

Do you have the Vista MBR installed on any of your hard disks?

John

 

[Jawade]

Yes, the Windows 2000/XP MBR boots Vista without problems, so does the
Windows 98 MBR, as long as you edit and restore the disk signature after
you install it.

What exactly do you mean by "the disk signature belongs to the
boot-partition"? The disk signature is used (combined) in the creation
of all partition signatures on the disk, if you have more than one
partition the disk signature was used in (is part of) all the partition
signatures. The three bytes at offsets 1B5-1B7 are used to display
error messages from the Master Boot Code.

Yes, I was wrong, the signature belongs to al the partitions on that
disk. If you have a second drive, the signature in his MBR belongs
to all the partitions on the 2th disk.

But I put a w98 IPL in the MBR, the disk signature ok, but the
pc did'nt boot up (Vista). No message. In the second partition
(Linux) he said No system found, even in the 3th (XP). It's a
triple boot system.

 

[John John]

Yes, I was wrong, the signature belongs to al the partitions on that
disk. If you have a second drive, the signature in his MBR belongs
to all the partitions on the 2th disk.

But I put a w98 IPL in the MBR, the disk signature ok, but the
pc did'nt boot up (Vista). No message. In the second partition
(Linux) he said No system found, even in the 3th (XP). It's a
triple boot system.

How did you change the IPL from GRUB/Lilo to W98?

John

 

[Timothy Daniels]

Interchangeable in what sense?

1- As on a Vista installation, can the Vista MBR be replaced
with the XP MBR?

or

2- As on a Windows XP installation, can the XP MBR be
replaced with the Vista MBR?

The answers are yes, no and maybe. I'll give you my full verdict
later on. jorgen raised a point about BitLocker functions in the
MBR, I'm looking into that, it appears that the MBR must be
TPM aware for BitLocker to work properly, so if one wants to
use BitLocker then other MBR's are unsuitable.

John

The original question concerned the claim in APCmag that
Vista's MBR had to be restored after an installation of XP in
which XP's installer had overwritten Vista's MBR with XP's
MBR - or would it be sufficient to merely restore the active
primary partition's Boot Sector (which points to ntldr). That
question would be 1).

Then, when "jorgen" made the claim that MBRs are all the
same (at least among Windows OSes), the question also arose
about whether Vista's MBR would be equally suitable for
booting XP (provided that the Boot Sector in the active primary
partition pointed to Vista's boot loader/manager). That would
be question 2).

If use of BitLocker affects the answers to 1) and/or 2),
I guess there should be questions 1a), 1b), 2a), and 2b),
in which a) is "BitLocker Off", and b) is "BitLocker On".

*TimDaniels*

 

[CZ]

Summary of results of running Win98 SE's fdisk /mbr on a Vista computer.
(note that the computer multi-boots between two Vista installs, one with SP1
and the other w/o SP1, and several installs of XP)

1) Did the disk signature change?
Yes, and Vista and XP automatically changed the partition signatures to
reflect the change (per a registry review).

2) Did vista load and run in the normal manner with the Win98 SE MBR and the
new disk signature?
For the Vista install w/o SP1: yes, it had zero problems.
For the Vista install with SP1: no. It would only boot into a temporary
profile, using either of two admin user accts. The drive enumeration system
was changed so that the Vista SP1 vol instead of being C: (the pre-test
drive letter), the vol now boots as I:. Note that both Vista vols were
installed via a DVD boot using the same TechNet DVD, so, the drive
enumeration system was not changed for the Vista vol that did not have SP1.

3) Manually changing the disk signature in sector 0 (the MBR) back to the
pre-test signature did not solve the problem with the Vista SP1 vol.


Notes
For non-Vista booting, drive C: is XP Home, meaning that Home was installed
before the other op system installs.

The computer has two hard disks, one has a single primary partition and an
extended partition, the other only has an extended partition (no primary).

 

[John John]

Summary of results of running Win98 SE's fdisk /mbr on a Vista computer.
(note that the computer multi-boots between two Vista installs, one with SP1
and the other w/o SP1, and several installs of XP)

1) Did the disk signature change?
Yes, and Vista and XP automatically changed the partition signatures to
reflect the change (per a registry review).

2) Did vista load and run in the normal manner with the Win98 SE MBR and the
new disk signature?
For the Vista install w/o SP1: yes, it had zero problems.
For the Vista install with SP1: no. It would only boot into a temporary
profile, using either of two admin user accts. The drive enumeration system
was changed so that the Vista SP1 vol instead of being C: (the pre-test
drive letter), the vol now boots as I:. Note that both Vista vols were
installed via a DVD boot using the same TechNet DVD, so, the drive
enumeration system was not changed for the Vista vol that did not have SP1.

3) Manually changing the disk signature in sector 0 (the MBR) back to the
pre-test signature did not solve the problem with the Vista SP1 vol.


Notes
For non-Vista booting, drive C: is XP Home, meaning that Home was installed
before the other op system installs.

*****************************************************

The computer has two hard disks, one has a single primary partition and an
extended partition, the other only has an extended partition (no primary).

That probably explains why one Vista installation booted and the other
didn't, the signature was change on one disk but not the second, the
installation on the disk with signature unchanged booted while the one
on the disk with signature changed didn't. Correct?

John

 

[Jawade]

How did you change the IPL from GRUB/Lilo to W98?

I have a Vista-MBR with my own bootmanager. I changed the IPL with
my own diskeditor with several copy-possibilities.

 

[CZ]

CZ wrote:
Summary of results of running Win98 SE's fdisk /mbr on a Vista computer.
(note that the computer multi-boots between two Vista installs, one with
SP1 and the other w/o SP1, and several installs of XP)

1) Did the disk signature change?
Yes, and Vista and XP automatically changed the partition signatures to
reflect the change (per a registry review).

2) Did vista load and run in the normal manner with the Win98 SE MBR and
the new disk signature?
For the Vista install w/o SP1: yes, it had zero problems.
For the Vista install with SP1: no. It would only boot into a temporary
profile, using either of two admin user accts. The drive enumeration
system was changed so that the Vista SP1 vol instead of being C: (the
pre-test drive letter), the vol now boots as I:. Note that both Vista
vols were installed via a DVD boot using the same TechNet DVD, so, the
drive enumeration system was not changed for the Vista vol that did not
have SP1.

3) Manually changing the disk signature in sector 0 (the MBR) back to the
pre-test signature did not solve the problem with the Vista SP1 vol.


Notes
For non-Vista booting, drive C: is XP Home, meaning that Home was
installed before the other op system installs.

*****************************************************

The computer has two hard disks, one has a single primary partition and an
extended partition, the other only has an extended partition (no primary).

That probably explains why one Vista installation booted and the other
didn't, the signature was change on one disk but not the second, the
installation on the disk with signature unchanged booted while the one
on the disk with signature changed didn't. Correct?

My response:
John:
The problem install was on disk00 which had its disk signature changed.
However, consider the following:
1) It did boot, but only into a temporary profile, which allowed me to look
for casual issues.
2) Manually changing the disk signature back to the pre-test value did not
solve the problem.
3) I did the same test about a year ago without any problems. I believe
that the same disk00 vol relationship was in use at that time, though I
cannot verify that it was.