Re: GRUB module query

On Saturday 19 August 2006 23:16, Tod Merley wrote:
Hi Again Dave (I hope everybody can forgive top posting and interwoven
replies but...),

Interwoven Replies:

On 8/19/06, Dave S <ubuntu@xxxxxxxxxxxx> wrote:
On Thursday 17 August 2006 22:15, Tod Merley wrote:
On 8/17/06, Dave S <ubuntu@xxxxxxxxxxxx> wrote:
Hi Dave!

Ahh my problem solved - I am no expert but I will tell you what I have
found. If I am wrong let me know - its the way i learn :)


My PCI raid controller has its own BIOS - when I boot it gives me a
config screen for various RAID options - I turn them off and use kernel
software RAID.

Interesting. The whole interaction between BIOS, apparently in your
case a secondary "on card" bios, and then GRUB, and then Kernel.
Bill has probably been criticised about his tendency to "take over the
world" thing but it DID make this whole area more regimented for his
world. In our case, I hope GRUBv2, new more Linux.NX aware BIOSs, and
super kernels will move some of this off of our desks.

I do not understand. If you need the raid driver to access the
disk then how can you even fully load GRUB?!?!

Because GRUB is loaded by the BIOS. On power up it is the BIOS that is
first started, the BIOS loads in the first few sectors of a HDD and
executes them - hello GRUB ! Only the first HDD light of my RAID array
flickers - its not in RAID mode yet.

So on boot the BIOS (and I guess my RAID card BIOS) conspire to load the
first few sectors of my RAID hdd - so far so good :)

(NOTE BIOSs are getting too smart - I used to have 2 x ide controllers on
the motherboard hda/b hdc/d. I plug in the raid card and the card assumes
hda/b hdc/d and my motherboard ide controllers are shifted to hde/f hdg/h
!)

So grub then asks the BIOS to load the kernel & initrd.img. initrd.img is
the temporary RAM root file system (very stripped down) - you can find it
in /boot and look whats inside by ...


linuxrc is executed about here - it checks the hardware, works out what basic
kernel modules are needed, loads them from the ramdisk initrd.img and ...


root@dave-comp:/boot# mkdir /tmp/tmpinitrd
root@dave-comp:/boot# cd /tmp/tmpinitrd/
root@dave-comp:/tmp/tmpinitrd# cat /boot/initrd.img-2.6.15-26-386 | gzip
-d | cpio -i --make-directories
31437 blocks
root@dave-comp:/tmp/tepinitrd# ls
bin conf etc init lib modules sbin scripts usr

Its a mini filesystem :)

Oh I was happy to see this, :) :) !! I knew about the ramdisk and
had intended to "unzip and reconstruct" one. I believe it will make a
very good "eyes on" part of my presentation. I have already run
through the procedure (for my Dapper) and done some "snooping" - all
recorded in WP. I may also make this the area to use when looking at
the filesystem hierarchy (requested by a LUG member).

Note the kernel has not accessed the HDDs yet, this exists entirely in
RAM. The kernel then starts and access this filesystem. Inside the
filesystem it executes /linuxrc to detect hardware and load appropriate
modules - all from this RAM filesystem.

Once the modules are loaded it then accesses the HDDs and changes its
root filesystem to the main HDD filesystem. (both HDD leds start blinking
on my HDDs - RAID is working :)

My problem was that /linuxrc could not detect and load the needed module.
My solution was ...

Who, from where, calls "linuxrc"?

linuxrc is a program that is started in the start-up stage of the kernel prior
to the actual boot process. This allows you to boot a small modularized
kernel and to load the few drivers that are really needed as modules.

from ...
http://www-uxsup.csx.cam.ac.uk/pub/doc/suse/suse9.1/adminguide9.1/ch12s04.html

You can also dip into initrd.img & open the file :) - cool isn't it :)



apt-get install initrd-tools
vi /etc/mkinitrd/modules
and add the line 'it821x'
apt-get install --reinstall linux-image-2.6.15-26-386

re-boot, the new initrd.img is loaded & everything works :)

Ahhhh! Soo happy to see the chicken and egg happy at the same time.

Thank you Dave! The presentation will be better, and those I run into
doing this mail list research who do have a "my egg has no chicken"
problem will be very happy to know this!

Thanks again!

Tod

No problem. I learnt a lot solving my problem & it is good to help someone
else. That way we all benefit :)

Good luck with the presentation

Dave



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