[rhelv6-list] module load order changed in initramfs

neo3 matrix neo3matrix at gmail.com
Tue Jan 11 14:30:11 UTC 2011


Hi Jon,

Thank you very much for replying.

The specific problem which I am facing is:-
I am working on a Linux disaster recovery product where we used to restore
the client to its original state after once we have a full backup of client.

While restoring the client, we boot the client with minimum os image
(actually with initramfs) .

Now, to properly boot the client using initramfs, *we need to provide proper
driver load order/sequence* to detect disks and other hardware, especially
for SCSI devices. Upto RHEL5, we can easily get the drivers and their
respective load order/sequence by just "grep"ing insmod or modprobe on the
"init" script.

In RHEL6, as per your comments, calls to modprobe made by udev decides
driver loading order and we can see very few module names in standard
script.

So, my question is how can I get the modules list and their load order from
initramfs?
If not from initramfs,  is there any other way to get it from a normal
running system?
This information is critical for me to provide proper drivers and their load
order during restoration.

Can you please give me some guidelines on this front?

--
Neo












On Tue, Jan 11, 2011 at 4:35 PM, Jon Masters <jcm at redhat.com> wrote:

> On Tue, 2011-01-11 at 16:04 +0530, neo3 matrix wrote:
>
> > Can anybody tell me what is the driver load order in RHEL 6 and how
> > can I find it out?
>
> Hello,
>
> Module loading for hardware devices in RHEL6 initramfs is determined by
> calls udev makes to modprobe, so in theory you will see very few as it's
> a standard script. The order of loading may change from RHEL5, but
> broadly follows the order in which the kernel enumerates devices.
>
> I specifically changed module load ordering in RHEL6 to remove the
> "parallel" loading approach taken in Fedora. That was cute for slight
> improvement in boot speed, but it undermined predictability. Therefore,
> the version of udev in RHEL6 will make *one call at a time*, and you
> should always see the same ordering on each boot.
>
> Can you let us know specifically what problem you are having? Possibly
> by filing a support case or opening a Bugzilla?
>
> Jon.
>
>
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