apurva mehta

Hi,

I just installed minix 2.0.0 on a vmware virtual machine running under
linux. So far it has been quite good. I have been able to recompile

I cannot add users to the system, though. I use the adduser script,
and it runs without any problems. If I type 'exit' as root just after
running adduser, I get a login prompt from where I can actually login
as the newly created user without problems.

However, if I poweroff the system and then power it back on, I cannot
login as the newly created users! I checked the /etc/passwd file and
the entry for my new user is missing.

The problem gets more interesting. When I went back to my
/usr/src/kernel directory, I found that all the object files I had
compiled were still present with proper date and time stamps.

Then I did a `touch test.txt' in /root and rebooted. On the reboot,
test.txt was missing.

I did a `touch test.txt' in /usr/apurva (apurva is the user I was
trying to create, the files created by 'adduser' are still
present). When I rebooted, the test.txt file was still there!

It looks to me that the changes root makes to certain directories are
not saved while they are saved in certain other directories. Can
anyone think of a logical explanation for this?

Regards,
- Apurva

andrew

It sounds like you are running off the ramdisk. Check the
bootmonitor setting. If you make changes to the root filesystem
(/) the changes will get lost at powerdown. The bootmonitor
variable rootdev should not be equal to ram. rootdev should
probably equal bootdev. This is just Minix and not vmware.
This would explain losing the root filesystems files and yet
keeping the /usr filesystems files.

kenichi takahagi

Your root filesystem may be on the RAM disk.
Check the boot parameter "rootdev".
See MONITOR(8).

--
Kenichi Takahagi

apurva mehta

"Andrew" <andrew@no_spam.org> writes:

Thanks, that did it.

So the root file system is stored entirely in the RAM by default?

Also, I see that the `ramimagedev' variable is set to `bootdev'. Does
this mean that the boot monitor loads the root filesystem image from
the boot device at boot up?

Correct me it I am wrong, but by setting the `rootdev' to `bootdev'
instead of `ram', I am instructing the boot monitor to transfer
changes made to the root device directly to the hard disk thereby the
state is saved in between sessions. When `rootdev' was set to `ram',

If what I am saying above is correct, what is the reason for the
`rootdev' variable to be set to `ram' by default. It does not make a
lot of sense.

Thanks,
- Apurva

philip

It is mostly historical. Initially, the root filesystem has to be the ramdisk
because otherwise it is not be possible to install (from floppies) on a
system with a single floppy drive. Before 2.0.0, the root device
was compiled into the image (FS) so there was no easy way to change it.

Furthermore, having the root on ramdisk allows you to experiment with
Minix without installing it on the harddisk.

There was also a performance argument. 16-bit Minix did not have a large
cache in FS. Using a ramdisk speeds things up a bit.

So, it seems that the current install script should simply change the
root device when installing on a harddisk.

However, if you damage the root filesystem, you can't boot anymore.
Minix is intended for experimenting with operating system code, so
this risk is quite real.


--
Everyone I've met who had any experience with the phenomenon have confirmed my
opinion that if a Ph.D. in computer science knows anything at all about
computers, it's probably pretty much an accident. -- J.D. Baldwin, in asr

apurva mehta

philip@pch.home.cs.vu.nl (Philip Homburg) writes:

OK. Thanks for the info. I guess with VMware and regular snapshots and
all those fancy features, one tends to think that screwing up
the root filesystem is not a problem at all. Just roll back to the
previous snapshot!

Regards,
- Apurva

kjb=733443

But it already does, at the very end:

edparams /dev/$root "rootdev=$root; ramimagedev=$root; $cache; save" || exit

Manual installation, maybe?
--
Kees J. Bot, Systems Programmer, Sciences dept., Vrije Universiteit Amsterdam

apurva mehta

kjb=733443@cs.vu.nl (Kees J Bot) writes:

Yes, I did a manual installation.

Regards,
- Apurva