Subject: Q: rom or flashrom root filesystem

From: Jungjun Kim <[email-masked]>
Date: Thu, 18 May 2000 10:26:42 +0900

Hello,

I would like to want to know how I can mount root filesystem from ROM or
FlashROM which are memory-mapped.
Because of memory-mapped (Flash)ROM which are not in RAM address space,
I'm not sure it is OK to use initial ramdisk.

Anyone has experience about this problem?

Thanks,

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From: "Hugo Fiennes" <[email-masked]>
Date: Tue, 23 May 2000 10:57:59 +0100

> Anyone has experience about this problem?

The empeg uses a 320k rom/flash disk (read only) for a halfway house boot
used when we upgrade the hard disk partitions/contents.

We do this just by setting the initrd start & end to point to the
appropriate place in flash (in our case I think it's 0xd00b0000 - 0xd0000000
is the base of flash in our memory map.

One thing you *do* have to patch is the code in arch/arm/setup.c which
checks to see if the initrd exists within physical RAM - obviously, it won't
in this case. Also, you can't use a compressed image as it's mounted
in-place without any RAM usage.

Hugo
empeg

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From: Nicolas Pitre <[email-masked]>
Date: Tue, 23 May 2000 10:05:44 -0400 (EDT)

> in-place without any RAM usage.

Are you sure of that?  AFAIK initrd's are never mounted in place,
compressed or not.  You need a special block device driver to mount
uncompressed filesystems directly from flash.

Nicolas