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 at mw-itcon.de] 
> Sent: Tuesday, March 21, 2006 1:14 AM
> To: Lakshmi N. Sundararajan
> Cc: linux-mtd at 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
>