Booting from JFFS2

Booting from JFFS2

[Bao C. Ha]

I would like to partition the Flash into two: (1) boot loader and 
(2) JFFS2.  Can I put the kernel, zImage, and fs.gz on JFFS2, 
and boot the kernel from there?  I would like to boot the kernel,
mount the fs.gz as cramfs, and mount the JFFS2 under /flash
as a writable storage.  Linux will be running exclusively in 
RAM.

Thanks.
Bao

Re: Booting from JFFS2

[David Woodhouse]

baoha@sensoria.com said:
> I would like to partition the Flash into two: (1) boot loader and  (2)
> JFFS2.  Can I put the kernel, zImage, and fs.gz on JFFS2,  and boot
> the kernel from there? 

The answer to that question is entirely dependent on the bootloader you 
use. But at the moment, I think there are no bootloaders which support this.

There are patches available for Compaq bootldr used on the iPAQ, which make
it capable of loading a kernel from a JFFSv1 filesystem. But nobody's yet 
done JFFS2, AFAIK. 

We're intending to add this support to RedBoot some time in the near 
future, hopefully.

--
dwmw2

Re: Booting from JFFS2

[Karl Pitrich]

On Tue, 15 May 2001, David Woodhouse wrote:

> baoha@sensoria.com said:
> > I would like to partition the Flash into two: (1) boot loader and  (2)
> > JFFS2.  Can I put the kernel, zImage, and fs.gz on JFFS2,  and boot
> > the kernel from there? 
> 
> The answer to that question is entirely dependent on the bootloader you 
> use. But at the moment, I think there are no bootloaders which support this.
> 

you could check zboot which is used in the yopy pda.
zboot resides on a separate part in the flash.
it is available at yopydeveloper.org under gpl.
i think the gmate guys are currently mangling their system to
jffs so this could work.

karl.

Re: Booting from JFFS2

[Nicolas Pitre]

On Tue, 15 May 2001, David Woodhouse wrote:

> The answer to that question is entirely dependent on the bootloader you
> use. But at the moment, I think there are no bootloaders which support this.
>
> There are patches available for Compaq bootldr used on the iPAQ, which make
> it capable of loading a kernel from a JFFSv1 filesystem. But nobody's yet
> done JFFS2, AFAIK.

Yes, JFFS2 is apparently done as well.


Nicolas

RE: Booting from JFFS2

[Bao C. Ha]

This is for a sh4-based board.  There are two boot loaders
available: lilo and ipl+sh.  From your answer, I assume
that none of the boot loader out there understands JFFS2
yet.

My next option is to partition the flash into three: (1)
bootloader, (2) ext2 for kernel/initrd, (3) JFFS2 for the
rest of the filesystem's mount points.

Thanks.
Bao

-----Original Message-----
From: David Woodhouse [mailto:dwmw2@redhat.com]On Behalf Of David
Woodhouse
Sent: Tuesday, May 15, 2001 12:11 AM
To: Bao C. Ha
Cc: linux-mtd@lists.infradead.org
Subject: Re: Booting from JFFS2



baoha@sensoria.com said:
> I would like to partition the Flash into two: (1) boot loader and  (2)
> JFFS2.  Can I put the kernel, zImage, and fs.gz on JFFS2,  and boot
> the kernel from there?

The answer to that question is entirely dependent on the bootloader you
use. But at the moment, I think there are no bootloaders which support this.

There are patches available for Compaq bootldr used on the iPAQ, which make
it capable of loading a kernel from a JFFSv1 filesystem. But nobody's yet
done JFFS2, AFAIK.

We're intending to add this support to RedBoot some time in the near
future, hopefully.

--
dwmw2

Re: Booting from JFFS2

[David Woodhouse]

baoha@sensoria.com said:
>  (1) bootloader, (2) ext2 for kernel/initrd, (3) JFFS2 for the rest of
> the filesystem's mount points.

Why ext2 for the second partition? Why not just 
 1. Bootloader
 2. Kernel
 3. JFFS2

--
dwmw2

RE: Booting from JFFS2

[Bao C. Ha]

I am looking for an easy way to update the kernel and
the fs image.  Ext2 will allow me to mount it, cp/rm
the compressed files: linux.gz and initrd.gz, umount
it and reboot.

It is probably not much different from flashing the
files on the JFFS2 partition then.  And initrd.gz
can be stored on the JFFS2 since the kernel knows
how to access it during bootup.

Thanks.
Bao

-----Original Message-----
From: David Woodhouse [mailto:dwmw2@redhat.com]On Behalf Of David
Woodhouse
Sent: Tuesday, May 15, 2001 9:16 AM
To: Bao C. Ha
Cc: linux-mtd@lists.infradead.org
Subject: Re: Booting from JFFS2 




baoha@sensoria.com said:
>  (1) bootloader, (2) ext2 for kernel/initrd, (3) JFFS2 for the rest of
> the filesystem's mount points.

Why ext2 for the second partition? Why not just 
 1. Bootloader
 2. Kernel
 3. JFFS2

--
dwmw2

Re: Booting from JFFS2

[David Woodhouse]

baoha@sensoria.com said:
>  I am looking for an easy way to update the kernel and the fs image.
> Ext2 will allow me to mount it, cp/rm the compressed files: linux.gz
> and initrd.gz, umount it and reboot. 

You shouldn't need an initrd - why can't the kernel use the JFFS2 as root 
filesystem? And you can put a kernel onto the flash partition directly, 
without having to use a filesystem.

--
dwmw2

RE: Booting from JFFS2

[Bao C. Ha]

Actually, using the JFFS2 as root will make our life simpler.
We will save on the Ram.

This is great suggestion!

Thanks.
Bao

-----Original Message-----
From: David Woodhouse [mailto:dwmw2@redhat.com]On Behalf Of David
Woodhouse
Sent: Tuesday, May 15, 2001 9:31 AM
To: Bao C. Ha
Cc: linux-mtd@lists.infradead.org
Subject: Re: Booting from JFFS2 



baoha@sensoria.com said:
>  I am looking for an easy way to update the kernel and the fs image.
> Ext2 will allow me to mount it, cp/rm the compressed files: linux.gz
> and initrd.gz, umount it and reboot. 

You shouldn't need an initrd - why can't the kernel use the JFFS2 as root 
filesystem? And you can put a kernel onto the flash partition directly, 
without having to use a filesystem.

--
dwmw2

Re: Booting from JFFS2

[Russ Dill]

>> makes in more interesting to flash it though

The Flashing takes place only once for JFFS2.
Then it will be just like a normal mounted
filesystem.

Right?

Bao

right, as long as you don't need to flash it all at once while booted