Bug 703673 – LiveUSB bad MBR-ID

Bug 703673 - LiveUSB bad MBR-ID


Summary:	LiveUSB bad MBR-ID

Status:	RESOLVED DUPLICATE of bug 708043
Duplicates:	709432 (view as bug list)

Classification:	openSUSE
Product:	openSUSE 12.1
Classification:	openSUSE
Component:	Live Medium
Version:	Milestone 2
Hardware:	i686 SUSE Other

Priority:	P2 - High Severity: Critical (vote)
Target Milestone:	---
Assigned To:	Steffen Winterfeldt
QA Contact:	E-mail List

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Reported:	2011-07-04 09:35 UTC by Bernhard Wiedemann
Modified:	2011-08-08 08:22 UTC (History)
CC List:	3 users (show)

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Description Bernhard Wiedemann 2011-07-04 09:35:42 UTC

MS2 and several Factory LiveCD-i686 isos since 2011-06-18 had 7fffffff as MBR-ID
making it fail to boot from HDD or USB mass storage.

Steps To Reproduce:
for f in factory/iso/openSUSE-*iso -mtime -40 ; do dd if=$f bs=1 skip=440 count=4 2>/dev/null | od -tx4|grep -q 7fffffff && echo bad $f ; done
bad factory/iso/openSUSE-GNOME-LiveCD-i686-Build0060-Media.iso
bad factory/iso/openSUSE-GNOME-LiveCD-i686-Build0063-Media.iso
bad factory/iso/openSUSE-GNOME-LiveCD-i686-Build0067-Media.iso
bad factory/iso/openSUSE-GNOME-LiveCD-i686-Build0069-Media.iso
bad factory/iso/openSUSE-GNOME-LiveCD-i686-Build0071-Media.iso
bad factory/iso/openSUSE-GNOME-LiveCD-i686-Build0072-Media.iso
bad factory/iso/openSUSE-GNOME-LiveCD-i686-Build0097-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0059-Media-.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0060-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0061-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0062-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0063-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0071-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0072-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0089-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0090-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0092-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0093-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0095-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0096-Media.iso
bad factory/iso/openSUSE-KDE-LiveCD-i686-Build0097-Media.iso

Comment 1 Bernhard Wiedemann 2011-07-19 07:43:35 UTC

I finally found out why some of those isos had a bad MBR id:

when isohybrid from syslinux-4 is called (on a 32bit system) with -i 0x80000000 or above, the value will be clipped to 0x7fffffff before being written into MBR thus causing it not to be found on USB-boot.
As the default is to use a random id, this would cause 50% of isos to be bad.

there are two possible ways to solve this: 

a) the most significant bit is cleared early enough (e.g. &=0x7fffffff right after parsing the -i param and after generating a random id value)

b) the whole code is made to work cleanly with 32-bit/unsigned id values

Comment 2 Stephan Kulow 2011-08-02 10:27:51 UTC

*** Bug 709432 has been marked as a duplicate of this bug. ***

Comment 3 Andreas Jaeger 2011-08-07 09:23:36 UTC

This seems to hit quite a lot of systems, raising priority.

Comment 4 Steffen Winterfeldt 2011-08-08 08:22:41 UTC

fixed some time ago

*** This bug has been marked as a duplicate of bug 708043 ***