Re: [CFT] initramfs patch

Eric W. Biederman
2001-07-31T06:53:08Z

Mike Touloumtzis <miket@bluemug.com> writes:

> On Mon, Jul 30, 2001 at 03:50:33PM -0500, Jeff Garzik wrote:
> > On Mon, 30 Jul 2001, Mike Touloumtzis wrote:
> > >
> > > 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.
>
> I think you're misunderstanding what I propose. I'm talking about
> having a device in /dev that would allow access to a filesystem
> image (cramfs or romfs) that would be embedded in the in-memory
> kernel image.

The current mtd drivers allow exactly this. Having a filesystem on
your flash or rom device. I don't think any filesystem that runs on
top of them currently supports XIP but the basic infrastructure is
there.

Eric