[U-Boot-Users] Run Linux kernel from within a JFFS2 filesystem

[U-Boot-Users] Run Linux kernel from within a JFFS2 filesystem

[Giuseppe Modugno]

Hi all,

this is my first post in this mailing list. I hope I don't start with a FAQ.

On my board I have installed U-Boot and I'm able to run Linux kernel and 
  rootfs via Flash/Flash (ramdisk/image file) or TFTP/NFS.

Of course, either ramdisk and nfs aren't suitable for my end application 
(ramdisk losts many RAM space and NFS won't be available).

So I'd like to use a local root filesystem stored in the NOR Flash (a 
J30 Intel), starting from the small ramdisk I have and adding all 
software I need.

I could divide my Flash memory in three partitions:
- U-Boot bootloader (with the two sectors for its configuration)
- Linux kernel image
- JFFS2 root filesystem

But I want to go futher and I want to save the linux kernel image file 
into the root JFFS2 filesystem. So I'll have only two main partitions:
- U-Boot bootloader (...)
- JFFS2 root filesystem (with linuk kernel image file saved inside)

Is U-Boot able to run a kernel image file that is saved into a JFFS2 
filesystem stored in the Flash? I think this is what happens on a 
desktop computer (where the bootloader is Grub and the root filesystem 
is on a hard-disk and the kernel is a file saved into it).

I think it isn't so simple for U-Boot that is capable of running the 
application (linux kernel in my case) only at a specified memory address 
(it doesn't have any knowledge about JFFS2 filesystem, do it?).

Many thanks for your comments and my compliments for the good work!

   Giuseppe

[U-Boot-Users] Run Linux kernel from within a JFFS2 filesystem

[Luigi 'Comio' Mantellini]

Ciao Pes?,

U-Boot can load an image from a jffs2 fs using the fsload command:

fsload DEST_ADDR imagename

Furthermore, you need to properly define the mtdpart and mtdids
environment vars or define the opportune #define, like this:

#define MTDIDS_DEFAULT          "nor0=phys_mapped_flash"
#define MTDPARTS_DEFAULT
"mtdparts=phys_mapped_flash:2M(jffs2),10M(root)ro,2M(u-boot)ro,2M(kernel)ro"

ciao,

luigi

Il giorno sab, 14/06/2008 alle 11.48 +0200, Giuseppe Modugno ha scritto:

> Hi all,
> 
> this is my first post in this mailing list. I hope I don't start with a FAQ.
> 
> On my board I have installed U-Boot and I'm able to run Linux kernel and 
>   rootfs via Flash/Flash (ramdisk/image file) or TFTP/NFS.
> 
> Of course, either ramdisk and nfs aren't suitable for my end application 
> (ramdisk losts many RAM space and NFS won't be available).
> 
> So I'd like to use a local root filesystem stored in the NOR Flash (a 
> J30 Intel), starting from the small ramdisk I have and adding all 
> software I need.
> 
> I could divide my Flash memory in three partitions:
> - U-Boot bootloader (with the two sectors for its configuration)
> - Linux kernel image
> - JFFS2 root filesystem
> 
> But I want to go futher and I want to save the linux kernel image file 
> into the root JFFS2 filesystem. So I'll have only two main partitions:
> - U-Boot bootloader (...)
> - JFFS2 root filesystem (with linuk kernel image file saved inside)
> 
> Is U-Boot able to run a kernel image file that is saved into a JFFS2 
> filesystem stored in the Flash? I think this is what happens on a 
> desktop computer (where the bootloader is Grub and the root filesystem 
> is on a hard-disk and the kernel is a file saved into it).
> 
> I think it isn't so simple for U-Boot that is capable of running the 
> application (linux kernel in my case) only at a specified memory address 
> (it doesn't have any knowledge about JFFS2 filesystem, do it?).
> 
> Many thanks for your comments and my compliments for the good work!
> 
>    Giuseppe
> 
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Ing. Luigi Mantellini
Industrie Dial Face S.p.A.
Via Canzo, 4 
20068 Peschiera Borromeo (MI)
Tel.: +39 02 5167 2813
Fax: +39 02 5167 2459
E-mail: luigi.mantellini at idf-hit.com


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