rgr

Hi,

The current Plan 9 which you download from Bell Labs is
uninstallable on a clean machine. It doesn't put the Master
Boot Record on the disk during the install process, and
various methods of writing an mbr (from another OS or from a
Plan 9 floppy) make the boot process survive only a split
second longer.

Note that if you currently have a working Plan 9 on the disk,
you have to wipe the MBR to replicate this problem. You can
do this by booting a dos disk and doing fdisk /mbr or with
dd. If you don't, you will install the latest Plan 9 and
it will seem to work fine, but only because the MBR survived
from your previous working setup.

I have replicated this behaviour on two computers of my own,
and even bought a brand new disk because I thought all my
disks might be screwed; and on top of that I went to friend's
house today and convinced him to take down his working Plan 9
and try a fresh install on a clean disk, and replicated it
there also.

--Rob

martin.althoff

Hello Rob Ristroph

I'll join in on that experience. 2 main boards, 3 hdd's tested.

I previously posted about partdisk being greedy... Hours of install
atempts later....

Replicateable steps and work around:
(with the aid of TomsRTBT linux 2.88 on CD)

1. Cleanup

boot Linux (I use TomsRtbt), execute dd if=/dev/zero of=/dev/hda
bs=1k count=10000
Zeroing just the mbr (bs=512 count=1) leads to the side effect later
if the same partitions are created again, plan9 fdisk will find the
old partitions. So the count value clobbers a bit more. Beware if you
have other partitions!!!!! Does anyone know where plan9 keeps the "sub
partitions info so I could kill that more "point blank"?? Then again
prepdisk should not pick up historic entries...

2. partitions
if you go to plan9 it cannot create partitions properly (as the others
described: In my case creating a partition less than the total hdd
size, resulted in the installer going back to partdisk. Inspecting
what it had done from Linux fdisk, I found a partion entry which had
the proper boundaries, but type set to "0". I tried lots of variants
of that theme none worked. Even giving it the whole disk (20GB) is
useless since the MBR does not work. Other fdisks (non plan9) cough up
about the format of the entries at times. Soooo.... stay in Linux
In Linux fdisk: create a new, blank partition table if working on a
zeroed disk. Write that. Now create the partions for plan9 that you
need. fdisk will set them to type 82 (linux) change that to type 39
(plan9, which fdisk knows) Write. Finished.

2b. You did not zero the disk since you are keeping other partitions:
use Linux fdisk to create the partitions anyhow. It works. Don't
rewrite the MBR from Plan9.

2c. using DOS fdisk /mbr creates a MBR that is only good for 2GB
partitions.

3. Plan9 will be happy now
continue with prepdisk, creating fs, swap,... It will see the
partition you have created and set to type 39


All the best,

Martin
martin.althoff@tiscali.co.uk

<<<<<================>>>>>

Tuesday, July 15, 2003, 6:17:43 AM, you wrote:

dbailey27

Same c-line for mbr. Then I redid the partitions.

Don

http://www.7f.no-ip.com/~north_