klibc - Apr 2005 - Query on Initramfs' and Initrd's coexistence

Hi

I am trying to have a built in initramfs along with the traditional initrd.
So I mount the initrd from the initramfs, but am facing problems in trying
to run the 'linuxrc'.

Following are the issues:

1. I mount the initrd from the initramfs and exceve 'linuxrc'.
   It starts executing linuxrc, but gives the following errors and panics:

Red hat nash version 3.4.42 starting
Loading jbd.o modules
insmod: QM_MODULES

ERROR: /bin/insmod exited abnormally!
Loading ext3.o module
insmod: QM_MODULES:

ERROR: /bin/insmod exited abnormally!
Mounting /proc filesystem
Creating block devices
failed to create /dev/hda
failed to create /dev/hda1
failed to create /dev/hda2
Creating root device
mkrootdev: mknod failed: 30
Mounting root filesystem
mount: error 2 mounting ext3
pivotroot: pivot_root(/sysroot,/sysroot/initrd) failed: 2
umount /initrd/proc failed: 2
Kernel panic - not syscing: Attempted to kill init!

2. This issue is irrespective of issue 1. I was wondering how I would be
spawning the real init after the real_root_dev has been mounted....
In the normal booting case(i.e. without initramfs) prepare_namespace()
returns and /sbin/init is executed
in init/main.c:init(). But, in the initramfs case, since prepare_namespace
is not called, this needs to be done in my init application on initramfs.
Klibc does not support threads. Am i right here? So when I 'exec'
linuxrc
after mounting initrd, it will never return to the calling function, and
all that linuxrc does is to pivot_root to the real_root_dev. How do I
execute the real init in this case?


Please tell me if I am missing something.

Thanks
Rachita.

On Wed Apr 6 03:46:28 PDT 2005 Rachita Kothiyal wrote:
> 2. This issue is irrespective of issue 1. I was wondering how I would 
> be
> spawning the real init after the real_root_dev has been mounted....
> In the normal booting case(i.e. without initramfs) prepare_namespace()
> returns and /sbin/init is executed
> in init/main.c:init(). But, in the initramfs case, since 
> prepare_namespace
> is not called, this needs to be done in my init application on 
> initramfs.
> Klibc does not support threads. Am i right here? So when I 'exec' 
> linuxrc
> after mounting initrd, it will never return to the calling function, 
> and
> all that linuxrc does is to pivot_root to the real_root_dev. How do I
> execute the real init in this case?
>
>
> Please tell me if I am missing something.
If you look closer you will notice that do_linuxrc is run in a seperate
process.  You should fork before execing linuxrc.

milton

Rachita Kothiyal wrote:
> 
> I am trying to have a built in initramfs along with the traditional initrd.
> So I mount the initrd from the initramfs, but am facing problems in trying
> to run the 'linuxrc'.
> 
Are you trying to support an arbitrary initrd, or a particular one? 
Supporting an arbitrary initrd requires duplicating all the conditions 
under which a legacy initrd is run.

	-hpa

> Are you trying to support an arbitrary initrd, or a particular one?
> Supporting an arbitrary initrd requires duplicating all the conditions
> under which a legacy initrd is run.
I am using initrd-2.4.20-18.9, which was being used by the default
kernel(2.4) on the RedHat installation on my machine. I am right now
working on 2.6.11-rc2 kernel. Is this version mismatch a problem?
I fail to understand why the linuxrc is erroring..What all does it expect
at this stage? I want to make sure that I have them all included...

Thanks
Rachita.

Hi

Has anyone tried hands on getting initramfs working along with the
traditional initrd(for loading modules etc.) ?
I was trying to, but get stuck towards the end of linuxrc, where it is
mounting the real root device..
It works fine if I use the real_root_dev(hard coded) instead of /dev/root
in the following line in linuxrc:
>>>mount -o defaults --ro -t ext3 /dev/root /sysroot
But with using /dev/root in the above, I get the following error:
"mount: error 6 mounting ext3"

I suppose it is unable to resolve /dev/root as the real_root_dev..Any help
on this would be great..

Thanks in advance
Rachita