i386/50887: MBR on kern.flp fails Compaq MBR validation on 4.5+

Brian Reid brian at reid.org
Sat Apr 12 21:50:05 PDT 2003


>Number:         50887
>Category:       i386
>Synopsis:       MBR on kern.flp fails Compaq MBR validation on 4.5+
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Apr 12 21:50:04 PDT 2003
>Closed-Date:
>Last-Modified:
>Originator:     Brian Reid
>Release:        FreeBSD 4.8-RELEASE i386
>Organization:
self
>Environment:
System: FreeBSD dhcp3.waverley.reid.org 4.8-RELEASE FreeBSD 4.8-RELEASE #0: Mon Mar 31 02:11:00 GMT 2003 root at freebsd-stable.sentex.ca:/usr/obj/usr/src/sys/GENERIC i386

Compaq Deskpro EN 733MHz Pentium III 

>Description:
	The floppy disk generated from floppies/kern.flp is not recognized
	as having a valid MBR unless the BIOS option "Verify MBR" is 
	disabled. Earlier 2.* and 3.* boot.flp disks that I tested worked
	fine. 4.7 and 4.8 both fail.
>How-To-Repeat:
	Get a Deskpro EN and try to boot from a floppy derived from
	kern.flp. It might fail on other Compaq models, too.
>Fix:
	The right fix would be to figure out why the Compaq BIOS is
	rejecting the MBR on that disk, and make it look like a 
	legal MBR. An obvious intermediate fix is to go into Setup
	and disable the "verify MBR" option under "Advanced". But
	I must confess I didn't figure that out until I had ripped
	the machine apart and added a CD ROM dangling by its IDE
	cable to do the actual install. 



>Release-Note:
>Audit-Trail:
>Unformatted:


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