Your message dated Sat, 2 Aug 2014 13:57:53 +0200 (CEST)
with message-id <alpine.deb.2.02.1408021352580.12...@cantor.unex.es>
has caused the report #725417,
regarding mbr: install-mbr wipes the disk-id portion of the MBR, rendering
Windows 7 unbootable
to be marked as having been forwarded to the upstream software
author(s) Neil Turton <neilt+...@chiark.greenend.org.uk>
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--
725417: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=725417
Debian Bug Tracking System
Contact ow...@bugs.debian.org with problems
--- Begin Message ---
Hello.
We have received this report from the Debian bug system.
[ The Debian maintainer, Santiago García, asked me for help to contact
you, but then I thought that first and foremost, the bug should be
forwarded "the Debian way". Thanks ].
---------- Forwarded message ----------
From: g1 <g...@libero.it>
To: Debian Bug Tracking System <sub...@bugs.debian.org>
Date: Sat, 05 Oct 2013 16:49:33 +0200
Subject: mbr: install-mbr wipes the disk-id portion of the MBR,
rendering Windows 7 unbootable
Package: mbr
Version: 1.1.11-5+b1
Severity: important
Tags: upstream
For years, I have run "install-mbr /dev/sda" on every hard disk where
I wanted to install Linux to its own partition, in addition to a
pre-existing Windows partition. Last time I did, it resulted in an
unbootable Windows 7 system. Here is what I discovered afterwards:
According to http://en.wikipedia.org/wiki/Master_boot_record, bytes
440--443 of the MBR are reserved for the Disk Id. Windows 7 (and likely
also Vista) stores that Id in its Boot Configuration Data (BCD) file,
and fails to boot unless the Id on disk matches the one in the BCD.
The install-mbr program copies the original MBR from disk into RAM,
overwrites the first 512 - 66 == 446 bytes with <internal> code, appends
the original partition table at offset 446, then writes the sector back
to disk. With the default <internal> code, the Disk Id is changed to
0x00000000, rendering W7 unbootable with overwhelming probability.
I don't know if bytes 440--446 of the <internal> MBR are useful code
or leftover garbage, therefore I'm not able to suggest a patch.
Please consider adding to the man page (and perhaps the executable itself)
a prominent warning against using install-mbr on a disk containing
Windows Vista or later.
For the record, I was able to restore the disk-id by examining the BCD
via hexdump, guessing the original id, and restoring it on disk via the
expert menu of the fdisk utility. Needless to say, I promptly purged
the mbr package from my system.
Best regards,
g
-- System Information:
Debian Release: 7.1
APT prefers stable
APT policy: (500, 'stable')
Architecture: i386 (i686)
Kernel: Linux 3.2.0-4-686-pae (SMP w/1 CPU core)
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/dash
Versions of packages mbr depends on:
ii libc6 2.13-38
mbr recommends no packages.
mbr suggests no packages.
-- no debconf information
--- End Message ---
