Re: [CFT] initramfs patch

From: Jeff Garzik (
Date: Mon Jul 30 2001 - 15:50:33 EST

On Mon, 30 Jul 2001, Mike Touloumtzis wrote:
> On Mon, Jul 30, 2001 at 02:05:55AM -0400, Alexander Viro wrote:
> > The thing unpacks cpio archive (currently - linked into the kernel image)
> > on root ramfs and execs /init. After that we are in userland code. Said
> > code (source in init/init.c and init/nfsroot.c) emulates the vanilla
> > 2.4 behaviour. You can replace it with your own - that's just the default
> > that gives (OK, is supposed to give) a backwards-compatible behaviour.
> One thing that would make embedded systems developers very happy
> is the ability to map a romfs or cramfs filesystem directly from
> the kernel image, avoiding the extra copy necessitated by the cpio
> archive. Are there problems with this approach?

Yes -- you need to at that point store initialized structures. Store
the dcache in its unpacked state on the ROM image, etc. That's the only
way to "map" a romfs directly. Otherwise there is ALWAYS an unpacking
or translation step between filesystem image and in-memory image.

Mapping an in-memory image directly may seem like a good idea, but it is
really not. ESPECIALLY for embedded folks.

Use a programmatic solution to unpack your filesystem... like say cpio
format in initramfs. :)


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