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Re: i386 mbr problem, again
- To: tech_(_at_)_openbsd_(_dot_)_org
- Subject: Re: i386 mbr problem, again
- From: Raan Young <raan_(_at_)_graand-visions_(_dot_)_com>
- Date: Thu, 03 May 2001 11:34:29 -0700
- Organization: Graand Visions, Inc
- Reply-to: raan_(_at_)_graand-visions_(_dot_)_com
> 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.
Note also that the original system would run Linux with no problem -- only OpenBSD failed.
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 installboot 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.
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