boot issue.

boot issue.

[Lakshmi N. Sundararajan]

Hello Team:
This may or may not be only related to MTD, but chances are someone
would be knowing
solutions for my case.

I have a compressed ext2 filesystem on a FLASH partition which I would
like
to use as a root file system mounted in RAM. The FLASH is accessed via
MTD layer.

The kernel parameters are "console=ttyS0,115200  noinitrd mem=128M
root=/dev/mtdblock5"
But kernel panics saying "VFS: Cannot mount root unknown device (31,5)".

If I were to use cramfs on FLASH and use the same kernel command line,
I am able to bringup the system.I am using 2.6 linux.

Would anyone know about this issue? Is there any thing I got to do?
Any pointers would be helpful.

Thanks,
-LN

Re: boot issue.

[Peter Menzebach]

Hi,

Lakshmi N. Sundararajan wrote:
> I have a compressed ext2 filesystem on a FLASH partition which I would
> like
> to use as a root file system mounted in RAM. The FLASH is accessed via
> MTD layer.
So you have *no* filesystem in the flash, but a compressed image. This 
is not usable as a filesystem directly in this format. Afaik, only the 
initrd code can use this...

> The kernel parameters are "console=ttyS0,115200  noinitrd mem=128M
> root=/dev/mtdblock5"
> But kernel panics saying "VFS: Cannot mount root unknown device (31,5)".
> 
which is correct, since there is no fs there...

> If I were to use cramfs on FLASH and use the same kernel command line,
> I am able to bringup the system.I am using 2.6 linux.
which would save the RAM space. You can still put some directories into 
RAM...

> Would anyone know about this issue? Is there any thing I got to do?
> Any pointers would be helpful.
The only solution I know is (assuming parallel flash) to give the 
compressed image as an initrd=<address>,<size> to the kernel.


Best regards
Peter
-- 
Peter Menzebach
Menzebach und Wolff IT-Consulting GbR
Phone +49 751 355 387 1

Re: boot issue.

[trimarchi]

Hi,
do you have u-boot as bootloader? Just read using nand read mem_address offset
size
then using the cmd line to pass this information to the kernel using initrd

Regards
Michael


Quoting Peter Menzebach <pm-mtd@mw-itcon.de>:

> Hi,
>
> Lakshmi N. Sundararajan wrote:
>> I have a compressed ext2 filesystem on a FLASH partition which I would
>> like
>> to use as a root file system mounted in RAM. The FLASH is accessed via
>> MTD layer.
> So you have *no* filesystem in the flash, but a compressed image. 
> This is not usable as a filesystem directly in this format. Afaik, 
> only the initrd code can use this...
>
>> The kernel parameters are "console=ttyS0,115200  noinitrd mem=128M
>> root=/dev/mtdblock5"
>> But kernel panics saying "VFS: Cannot mount root unknown device (31,5)".
>>
> which is correct, since there is no fs there...
>
>> If I were to use cramfs on FLASH and use the same kernel command line,
>> I am able to bringup the system.I am using 2.6 linux.
> which would save the RAM space. You can still put some directories 
> into RAM...
>
>> Would anyone know about this issue? Is there any thing I got to do?
>> Any pointers would be helpful.
> The only solution I know is (assuming parallel flash) to give the 
> compressed image as an initrd=<address>,<size> to the kernel.
>
>
> Best regards
> Peter
> -- 
> Peter Menzebach
> Menzebach und Wolff IT-Consulting GbR
> Phone +49 751 355 387 1
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
>



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RE: boot issue.

[Lakshmi N. Sundararajan]

(This thread is no way related to mtd. Just wanting to update interested

  members)

Hi Peter,
Thanks for your response. After some effort, I found that it is
possible.
It needs some changes in the linux kernel.

One could boot from a floppy which has a compressed root file system on
it.
(Note, not an initrd) The code path is similar to it, except that the
compression 
is now on FLASH. The code in prepare_namespace() recognizes this case
only 
when booted from floppy.

Instead now I changed it to recognize flash also in a similar way to
floppy.
    is_floppy = (MAJOR(ROOT_DEV) == FLOPPY_MAJOR ||
                MAJOR(ROOT_DEV) == 31);

This is all the change required.
Now the system boots fine.

Thanks,
-LN



> -----Original Message-----
> From: Peter Menzebach [mailto:pm-mtd@mw-itcon.de] 
> Sent: Tuesday, March 21, 2006 1:14 AM
> To: Lakshmi N. Sundararajan
> Cc: linux-mtd@lists.infradead.org
> Subject: Re: boot issue.
> 
> 
> Hi,
> 
> Lakshmi N. Sundararajan wrote:
> > I have a compressed ext2 filesystem on a FLASH partition 
> which I would
> > like
> > to use as a root file system mounted in RAM. The FLASH is 
> accessed via
> > MTD layer.
> So you have *no* filesystem in the flash, but a compressed 
> image. This 
> is not usable as a filesystem directly in this format. Afaik, 
> only the 
> initrd code can use this...
> 
> > The kernel parameters are "console=ttyS0,115200  noinitrd mem=128M
> > root=/dev/mtdblock5"
> > But kernel panics saying "VFS: Cannot mount root unknown 
> device (31,5)".
> > 
> which is correct, since there is no fs there...
> 
> > If I were to use cramfs on FLASH and use the same kernel 
> command line,
> > I am able to bringup the system.I am using 2.6 linux.
> which would save the RAM space. You can still put some 
> directories into 
> RAM...
> 
> > Would anyone know about this issue? Is there any thing I got to do?
> > Any pointers would be helpful.
> The only solution I know is (assuming parallel flash) to give the 
> compressed image as an initrd=<address>,<size> to the kernel.
> 
> 
> Best regards
> Peter
> -- 
> Peter Menzebach
> Menzebach und Wolff IT-Consulting GbR
> Phone +49 751 355 387 1
>