Moving Fedora 9 Hard Disk To Another System

[Paul Johnson]

On Thu, Nov 20, 2008 at 2:42 PM, Mikkel L. Ellertson
<mikkel at infinity-ltd.com> wrote:
> Paul Johnson wrote:
>>
>> When the kernel is updated, the Fedora 9 framework will rebuild a new
>> initrd and it will  NOT have the special modules in it.  On fedora
>> systems, I found no simpler solution than to edit the new-kernel
>> script and change the modules that were assumed.   Otherwise, the boot
>> up will fail just like you have been seeing.  On Ubuntu linux, I've
>> learned that the required modules can be configured in
>> /etc/modprobe.conf or someplace similar, and the initrd builder takes
>> notice of it.
>>
> What I have done in the past is to boot off the install media,
> select the rescue mode, and then chroot to where the root file
> system is mounted. I thin build the new initrd, making sure it
> matches the kernel I plan to boot from. In the future, installing a
> new kernel will build the initrd, using the information from the
> running kernel. At least it has worked correctly for the last 5
> updates on this machine sense I moved the drive here, and rebuilt
> the initrd for this motherboard.
>
> Mikkel
>
Unless you understand the mechanism through which the new initrd is
built, you cannot be confident in your statement that the new kernel
will be "using the information from the running kernel," as you put
it.  As far as I know, that is just wrong.  The initrd is built by the
new-kernel script, and it has no way of "talking to" the existing
kernel and getting the correct modules.
Instead, it is reading some configuration files under /etc, and
apparently you are lucky to have those files set correctly, but you
don't have any good reason to expect OP has same lucky configuration.

I'm not on a Fedora 9 system now, but I can tell you about Centos 52,
and it matches my memory of Fedora 8.  Fedora uses a script

/sbin/new-kernel-pkg

to handle the building of the initrd.  In that file, it calls
mkinitrd.  That file does not specify any options or modules to
pre-load.  When I want to be absolutely sure a module is loaded, I
have sometimes written them into that file.  But you see it just uses
mkinitrd without options.  So you go read mkinitrd man page, and it is
not entirely too clear about how the required modules are to be
specified, but it does say it reads "/etc/modprobe.conf" and
"/etc/modules.conf".   Note the preload option in mkinitrd is probably
where you need to focus.  Look in /etc/modprobe.conf on this Centos
system, and it has components like this:

alias scsi_hostadapter ata_piix

I am pretty sure that mkinitrd is taking note of that and using the
modules for ata_piix to get motherboard connectivity.

In the past, when I have wanted to know FOR SURE what modules are
needed, I make a small custom install on the machine in question.
Don't bother about configuring it.  Then I copy the modprobe.conf file
and the stuff in modules.conf if it exists.  Then you can go ahead and
install your standard disk image.  THen boot off a rescue disk, use it
to go into the new system and fix the modules so they are proper and
rebuild initrd.  Because you have fixed modprobe.conf, then new
kernels installs will get the right settings.

Sorry if this appears pedantic. I'm a teacher :)

PJ



-- 
Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas