RomFS

[Ruedi.Hofer at ascom.ch]

> Hi

Hi!

> That sounds good and it works. snip
>
> But how can I mount this rom/ramdisk from the kernel as its root disk?

Well, um, you can't.
I guess you have to write a simple read-only block device driver yourself...
I think i've seen a posting before by a guy alex at signum.se who has written
a flash file system, you might be able to steal some code from him.
Search the linuxppc-dev and linuxppc-embedded lists.

> What do I have to supply as boot parameter?
>
> I would like to store the entire application in the flash (kernel + application)

If you have enough ram, make an initrd and load with 8xxrom (I don't remember
the command, but i've done it.)

But be sure to check/fix the ramdisk, it might be broken.

I don't know your budget, but small ATA-Flash cards are cheap.
And really nice.

I've got a almost-working pcmcia driver waiting to be bugchecked
and released here...

And 8xxrom boots from ATA-Flash too.

Cheers /

Magnus

> \Ruedi
>
> damm at kieraypc01.p.y.ki.era.ericsson.se on 31.01.2000 16:23:22
> An: Ruedi.Hofer at ascom.ch @ MailGate
> Kopie:
> Thema: Re: RomFS
>
> > Hi,
>
> Hi!
>
> > My ADS board is happily running with a NFS mounted linux box.
>
> Great!
>
> > Now I have to put all the code into the flash memory to get a standalone
> > solution.
> >
> > I'm using the 8xxrom Bootloader. In a file called config.h I can configure
> > CONFIG_DISK_ROM.  As far as I can see, the bootloader assumes
> > then that a complete FAT filesystem is stored from the position
> > 0xFE020000 in flash.
> >
> > My question:
> > - Is my assumption right?
>
> Well, there is a file in the disk directory called rom.c.
> It is a simple read-only block driver for 8xxrom.
> It does not know anything about filesystems, so you can use any filesystem you want
> as long it is supported by 8xxrom.
>
> In rom.h can you find a define called ROM_DISKSTART which is the start address
> of the filesystem.
>
> > - How can I produce a FAT filesystem in a file, which I can download
> >   with MPC8BUG into the onboard flash?
>
> You have to look somewhere on the net.
> I usually create a ramdisk and make a filesystem and copy my things to it.
> Then I umount it and use dd to copy the data to a file which I burn to
> a flash.
>
> > - Does it have anything in common with the romfs driver which is supported
> >   by the kernel? (I think not)
>
> Nope.
> But it would sure be great if we could read one romfs image from the 8xxrom.
>
> Good luck /
>
> magnus