[Techtalk] booting a diskless client

Maria McKinley maria at shadlen.org
Mon Sep 29 23:46:17 UTC 2008

Rudy Zijlstra wrote:
> Maria McKinley wrote:
>> Maria McKinley wrote:
>>> Hello there,
>>> I am trying to boot a machine over the network, and it gets as far as 
>>> looking for /sbin/init, and then I get a kernel panic.
>>> I know that it is mounting the root directory, because if I eliminate 
>>> the directory /sys, it complains that it cannot mount sys. I know 
>>> that the file init exists in the root directory, and works with the 
>>> server.
>>> nina:~# file /tftpboot/oscar/sbin/init
>>> /tftpboot/oscar/sbin/init: ELF 64-bit LSB executable, x86-64, version 
>>> 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.8, 
>>> stripped
>>> nina:~# ls -lh /tftpboot/oscar/sbin/init
>>> -rwxr-xr-x 1 root root 37K 2008-09-29 13:32 /tftpboot/oscar/sbin/init
>>> nina:~# ls -lh /sbin/init
>>> -rwxr-xr-x 1 root root 37K 2008-08-12 07:20 /sbin/init
>>> nina:~#
>>> I don't understand why it believes that /sbin/init isn't there!
>>> Any advice would be awesome.
>>> thanks,
>>> maria
>> Now I am really confused. I was curious, so tried truly making 
>> /sbin/init not be there, and now the machine appears to get stuck 
>> trying to mount root. The console is just full of trying to mount and 
>> server not responding messages. Bloody hell, that makes no sense.
>> But then the server logs say this:
>> Sep 29 13:36:57 nina mountd[2616]: authenticated mount request from 
>> for /tftpboot/oscar (/tftpboot)
>> Sep 29 13:36:58 nina mountd[2616]: authenticated mount request from 
>> for /tftpboot/oscar (/tftpboot)
>> Sep 29 13:36:58 nina mountd[2616]: refused unmount request from 
>> for /root (/): not exported
>> Which I think means that it is trying to unmount the root directory, 
>> but calling it the wrong name. Or something. But I have no idea why, 
>> and none of this makes a lick of sense to me. Blech.
>> thanks,
>> maria
> Hi Maria,
> What is in the /etc/exports of the file server?
> it looks like the relevant directories are not exported by the file server.
> Cheers,
> Rudy

# /etc/exports: the access control list for filesystems which may be 
#               to NFS clients.  See exports(5).
# Example for NFSv2 and NFSv3:
# /srv/homes       hostname1(rw,sync,no_subtree_check) 
# Example for NFSv4:
# /srv/nfs4        gss/krb5i(rw,sync,fsid=0,crossmnt,no_subtree_check)
# /srv/nfs4/homes  gss/krb5i(rw,sync,no_subtree_check)
/usr  ,sync,no_root_squash)

tftpboot has all of the root directories. I've been trying to think of 
how I could no for sure that the root directory was getting mounted, but 
not sure how to do this. I thought that deleting the sys directory on 
the mount, and then having it complain that it wasn't there was pretty 
conclusive, but now I am wondering if I have missed something in my logic.


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