On Thu, 2003-10-09 at 11:04, Ed Skinner wrote:
> On Thursday 09 October 2003 10:36, Alan Dayley wrote:
> > Papacostantinou, Phillip wrote:
> > > Hi,
> > >
> > > I am designing an embeded computer product, using a Pentium-M processor
> > > board
> > > with a Flash Disk (for holding the runtime Image and loading it into the
> > > Processor Memory).
> >
> > Very nice.
> >
> > > The operating system (kernel) will be Linux.
> > > I do not have a hard disk (or any other storage device) as part of this
> > > system ie no storage device to write to.
> > >
> > > I have been told that Linux will not be able to wok without a File
> > > System, ie without a hard disk.
> > >
> > > Is anyone aware or able to comment with certainty on this subject ??
> >
> > Well, Linux needs a files system but it can use romfs for these
> > situations. It is done all the time.
> >
> > > Would the Linux Operating System be able to be configured to run without
> > > a hard disk or any file system ?
> > > If NO, Is there a way of tricking Linux to think that a File System
> > > is present, but rather in memory ?
> >
> > Google for romfs. Also, look around on linuxdevices.com for more
> > information on embedding Linux in this type of hardware. Also, an
> > EXTREMELY good resource for this question is the plug-devel list. Post
> > this same email there and experts will answer. There are members there
> > that do this sort of thing all the time.
> >
> > > I thank you in anticipation.
> >
> > You are welcome.
> >
> > Alan
>
> A small RAM fs is sometimes needed for transient things. Regardless, as
> Alan points out, Linux runs just fine without a hard disk. (Shameless plug:
> http://www.rytetyme.com/ is my company and "embedded Linux without a disk" is
> what we do most of the time.)
> You might also want to get a copy of "Building Embedded Linux Systems" by
> Yaghmour (O'Reilly is the publisher) in these regards. It is A#1 excellent.
More shameless plugs!
http://www.embeddedx86.com
What you are doing is exactly we are doing, except that we are PC/104.
Anyways, as everybody else said, you don't need a "hard disk". If what
you are doing involves a single application without the need for a
GNU/Linux OS, no logins, etcetera, then you can load an initrd image
that loads up your application instead of going through runlevels and
the like.
Also check out busybox. It has the "just needed" parts of various GNU
utilities (i.e, grep isn't full fledged, it only supports the more
common command line switches) into one binary, with symlinks for each
program (grep is a symlink to /bin/busybox) to the busybox binary.
And of course, there's uCLinux, a libc replacement of sorts that targets
small, embedded targets. Actually, it targets MMU-less machines. It's
side affect is smaller compiles.
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