[syslinux] Passing one more file after initrd to the kernel...

[Paolo Salvan]

Hi!

Some question about the first possibility you suggested (the second is
too far away...):

- initramfs is only on 2.6 kernel, or is on 2.4 also?

- initrd are usually gzipped...right? But these cpio files are also
gzipped? Are they all gzipped together, or only one at a time? In the
second case, should it be possible for the bootloader to append
on-the-fly to the main initramfs file an extra file, creating on-the-fly
the cpio header? Would this be the simplest way to get a second external
boot file usable from the linux environment, in your opinion?

bye!

Paolo


"H. Peter Anvin" ha scritto:
> 
> Paolo Salvan wrote:
> > Hi!
> >
> > I have a particular need... I'm not sure if this is the right place to
> > ask, but surely here there are people that can say me if it is feasible
> > or not...
> >
> > I'm working for a thin-client distribution (thinstation.sf.net); I want
> > to boot it from various media (netowork, cdrom, hd, usb key...), and at
> > the moment syslinux/isolinux/pxelinux are doing it very well...
> >
> > The problem is that the distribution is composed by a kernel, an initrd
> > and a CONFIGURATION TEXT FILE, some kb-long, that should be read by the
> > system after boot...
> >
> > At the moment I'm solving the problem instaling modules for all the unit
> > types (cd, hd, usb...) and fs (iso, fat), mounting the boot unit and
> > reading this file after boot...
> >
> > It would be quite a cleaner solution if I could pass this file to the
> > system directly during the boot phase, tghether woth kernel params and
> > initrd... and later if I could read this file in someway after the boot
> > (ie in the dev/ or proc/ path)
> >
> > In this way the file would be read using BIOS drivers, and if the system
> > can boot I would be sure that my conf file would also be read, without
> > needing to know which filesystem the system has been booted from, and
> > without requiring my mini-system to have a lot of driver used only to
> > load this small file...
> >
> > Does someone have some idea?
> 
> This can be done with initramfs, although right now it's a bit clumsy.
> However, initramfs is simply one *OR MORE* cpio archives strung
> together; if your config file thus could be wrapped into a cpio header
> and appended to the initramfs that would do the job.
> 
> Right now syslinux et al don't have any support for loading more than
> one file, but it has been somewhere on my list of things to do.  Another
> possibility would of course be to make this possible to do from a com32
> file; it technically speaking already is, but you have to load the
> kernel image and initramfs image yourself and then use the "terminate
> and replace boot code" function with a small stub that puts everything
> into the right place and invokes the kernel.  Definitely messier than it
> should be, and requires quite a bit of low-level hacking knowledge.