Cramfs root file system

Cramfs root file system

[Flavio Pereira]

Hi All

Im trying to use a cramfs image as a root-file system at kernel boot
time.

I've built a cramfs image, copied it into my flash device (mtd3), and
can successfully mount it at runtime.

However at boot time I use root=dev/mtdblock3 (or dev/mtd3 im not sure
which one to use) and I get the following errors...

NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
Root-NFS: No NFS server available, giving up.
VFS: Unable to mount root fs via NFS, trying floppy.
request_module[block-major-2]: Root fs not mounted
VFS: Cannot open root device "mtdblock3" or 02:00
Please append a correct "root=" boot option
Kernel panic: VFS: Unable to mount root fs on 02:00

Now, is it possible to do what Im trying to do, if so are there any
suggestions as to what I'm doing wrong?

Thanks
Flavio Pereira

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Re: Cramfs root file system

[Gerhard TAEUBL]

Hi!

First try root=/dev/mtdblock3 rw.

I try a long time ago this with my 'flashdisk' I copied at runtime all needed files, and reload the kernel (I use the comandline as fixcoded string..) and it works. Important is, that the kernel supports your filesystem at boottime! I think it isn't a good idea to use it as module!

Have fun
Gerhard

>>> "Flavio Pereira" <flavio.pereira@za.flextronics.com> 11/21/02 12:09pm >>>

Hi All

Im trying to use a cramfs image as a root-file system at kernel boot
time.

I've built a cramfs image, copied it into my flash device (mtd3), and
can successfully mount it at runtime.

However at boot time I use root=dev/mtdblock3 (or dev/mtd3 im not sure
which one to use) and I get the following errors...

NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
Root-NFS: No NFS server available, giving up.
VFS: Unable to mount root fs via NFS, trying floppy.
request_module[block-major-2]: Root fs not mounted
VFS: Cannot open root device "mtdblock3" or 02:00
Please append a correct "root=" boot option
Kernel panic: VFS: Unable to mount root fs on 02:00

Now, is it possible to do what Im trying to do, if so are there any
suggestions as to what I'm doing wrong?

Thanks
Flavio Pereira


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: Cramfs root file system

[Dennis Khoo]

Flavio,

> Please append a correct "root=" boot option
> Kernel panic: VFS: Unable to mount root fs on 02:00
>
> Now, is it possible to do what Im trying to do, if so are there any
> suggestions as to what I'm doing wrong?
>

I saw the same error when I was trying to mount jffs2 as root.  Maybe your
problem is similar to mine.

My solution:

1)   in kernel file init/main.c 's dev_name_struct,  add entry for
 "mtdblock", 0x1f00
if it's not there already.

2) in ppcboot =>setenv bootargs init=/linuxrc root=/dev/mtdblockx

Hope this helps.

Dennis Khoo
Software Engineer
Adapcom, Inc


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RE: Cramfs root file system

[Flavio Pereira]

Hi all / Dennis

>1)   in kernel file init/main.c 's dev_name_struct,  add entry for
> "mtdblock", 0x1f00
>if it's not there already.
>
>2) in ppcboot =>setenv bootargs init=/linuxrc root=/dev/mtdblockx

I added the mtdblock entry and, yes it seems to have helped. The kernel
however now returns...

mtdblock_open
ok
mtdblock: read on "initrd" at 0x400, size 0x400
mtdblock: read on "initrd" at 0x0, size 0x1000
mtdblock: read on "initrd" at 0x1000, size 0x1000
mtdblock: read on "initrd" at 0x2000, size 0x1000
mtdblock: read on "initrd" at 0x3000, size 0x1000
wrong magic
VFS: Mounted root (jffs filesystem) readonly.

Ive looked at the kernel code, and it looks like it doesn't support a
cramfs system only jffs (ROM systems anyway). Can anyone confirm whether
Linux 2.4.4 supports cramfs for root file systems?

Thanks
Flavio Pereira


-----Original Message-----
From: Dennis Khoo [mailto:dkhoo@atmxdsl.com]
Sent: Thursday, November 21, 2002 9:18 PM
To: Flavio Pereira; LinuxPPC
Subject: Re: Cramfs root file system

Flavio,

> Please append a correct "root=" boot option
> Kernel panic: VFS: Unable to mount root fs on 02:00
>
> Now, is it possible to do what Im trying to do, if so are there any
> suggestions as to what I'm doing wrong?
>

I saw the same error when I was trying to mount jffs2 as root.  Maybe
your
problem is similar to mine.

My solution:

1)   in kernel file init/main.c 's dev_name_struct,  add entry for
 "mtdblock", 0x1f00
if it's not there already.

2) in ppcboot =>setenv bootargs init=/linuxrc root=/dev/mtdblockx

Hope this helps.

Dennis Khoo
Software Engineer
Adapcom, Inc


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/