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Re: i386 mbr problem, again



On Thursday 03 May 2001 13:34, Raan Young wrote:
> > i don't know if this is the same problem you're refering to, but i've
> > used the latest snapshot floppy28.fs, snapshot binaries and a 'fresh'
> > disk (ie never had bsd on it before) and it cannot create a bootable
> > system.
>
> I think I missed the original question, but since this sounds exactly
> like a problem I've had, I'll pass on my conclusions.
>
> I attempted, a while back, to install 2.8 on an old 486/66 system.  The
> install process would work more-or-less, but when it came time to boot
> off the newly created system (on the hard drive) it would always fail.
>
> After a lot of experimenting, I came to the conclusion that OpenBSD
> *needs* LBA support from the BIOS -- even if the hard drive is smaller
> than 512MB -- in other words OpenBSD assumes LBA support, period.  Note
> that this conclusion is empirically derived and the actual problem may be
> some other subtle gotcha.  All I know is that a system with extremely
> similar hardware, and a BIOS that supported LBA, worked fine -- I could
> even boot off the hard drive built on the original system.
>

Try booting a Windows rescue diskette and running

a:> fdisk /mbr

Your problem is a FAQ.

> Note also that the original system would run Linux with no problem --
> only OpenBSD failed.
>
> Raan
>
>
> For those who care, here are the gruesome details...
>
> ... even if I use a drive that is less than 512MB, I still cannot get
> things to work properly.  During the install, fdisk reports that sysctl
> is claiming the drive is unconfigured.  Fdisk then seems to get the CHS
> values from the disk, but it also complains about LBA being the only
> valid access mode for partition 3.  Fdisk builds partition 3 with an
> incorrect ending section number.  Continuing the install, disklabel also
> reports the sysctl error and complains about LBA for partition 3. 
> Finally installb ot aborts with an error about not knowing the S and H
> values.
>
> At this point, if I reboot, the system hangs after putting out a message
> about using drive 0 partition 3.
>
> If I manually run fdisk, disklabel, and installboot, supplying the values
> as reported by the disk, then I can repair the disk such that a reboot
> gets a bit further -- it produces the boot> prompt, but then reports that
> /etc/boot.conf is an invalid argument.  The system acts as if it cannot
> read the hard drive -- even though it just found the boot tracks and got
> into the boot process.  The "machine diskinfo" command to boot doesn't
> even list the hard drive.
>
> If I boot from the install floppy and then interrupt the boot and attempt
> to boot the hard drive system, I get the same "no hard drive" behavior. 
> Yet if I let the floppy boot complete, I can then mount the hard drive
> and access the file system with no problem.