preliminary patch for initrd support in Mach

[Jérémie Koenig]

Hello,

As part of my debian-installer project[1] I have been working on
initrd support for GNU Mach. The new boot script command
$(devname=ramdisk-create) causes the contents of the module to be
copied into newly allocated memory which is made available to user
space through the device ${devname}.

The current version of my d-i images use this as the root filesystem,
with grub loading an ext2 filesystem image from the boot CD. Which is
not that good considering that the required free space on / will
likely vary from installation to installation. So a better solution
will be needed in the long run (union a tmpfs over / early on?)

There were also concerns raised on #hurd that this is not quite
hurdish and that its scope should be as limited as possible (read-only
gzipped data to be handled by userspace), or that modifying Mach for
this purpose is misguided and should be avoided (for instance by
embedding the initrd in a dedicated section of an elf module). Since
this is only needed for debian-installer, I beleive it could be kept
as a Debian patch until a more satifying solution is implemented.

My goal is to get a basic installer working as soon as possible, so
I'm going to move on to the other parts of my project for now unless
some critical problem with the attached patch shows up. However I
intend to return to this as soon as possible and I would appreciate if
we could discuss it in the meantime.

Thanks,

-- 
Jérémie Koenig <jk@jk.fr.eu.org>
http://jk.fr.eu.org/

[1] http://www.bddebian.com:8888/~hurd-web/user/jkoenig/

50_initrd.patch
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