YAIRD -- Yet Another MkInitRd
=============================

This is a proof of concept rewrite of mkinitrd, intended to test the
idea that we can get a more accurate picture of the modules needed
to boot a linux system by fully utilizing the information in sysfs.
It comes with templates that make it possible to generate different
initrd or initramfs images for different distributions.


Installation
============

Two perl modules need to be installed before using the application:

    --	HTML::Template.  This is a standard package under Debian,
    	in Fedora FC3 available via extras.
    --	Parse::RecDescent.  In Debian known as libparse-recdescent-perl,
    	in Fedora FC3 as perl-Parse-RecDescent.

Unpack, then configure and install:

	$ ./configure --prefix=$HOME/local
	$ make install

This installs a main configuration file ($HOME/local/etc/yaird/Default.cfg)
that specifies what the generated images should do.  In addition to this,
a template file is needed, that tunes this for the distribution in use.
Pick one from the provided examples, and copy it to the default location:

	$ cd $HOME/local/etc/yaird
	$ cp Debian.cfg Templates.cfg

If you want to regenerate the html documentation, you need the xmlto
package.

If you're installing from version control rather than a tarball,
you'll also need to have automake and autoconf available, and
need to run bootstrap.sh before doing 'configure; make'.


Installing with klibc
=====================

Yaird comes with a small C programs, and to avoid the overhead of the GNU
C library, you may want to compile this with klibc.  Note however that
this is only effective if every other program that is copied to the
initial root filesystem (such as mount, mknod and a shell) is compiled
in the same manner.

Recent versions of klibc provide klcc, a wrapper around gcc that makes
it easier to port programs to klibc.  Installation is faily simple;
the most important point is to make a symlink to a configured linux
source tree.  The SHLIBDIR determines where the shared library version
ends up.  If you want to use klibc for programs used early in the
boot process it makes sense to put it on the root file system.

You will need klibc 1.0.14 or newer.

	$ cd klibc-1.0.14
	$ ln -s /usr/src/linux... linux
	$ make bindir=$HOME/local/bin \
		mandir=$HOME/local/man \
		INSTALLDIR=$HOME/local \
		SHLIBDIR=$HOME/local/shlib \
		install
	$

Once you have klibc, you can configure yaird to make use of it
as follows:

	$ ./configure CFLAGS=-static CC=$HOME/local/bin/klcc \
		--prefix=$HOME/local
	...
	$ make install

The use of CFLAGS=-shared is optional.


Installing with uclibc
======================

To use uclibc rather than glibc or klibc:
 - Install uclibc.
   on debian, this can be done with "apt-get install uclibc-toolchain".
 - Verify that /usr/bin/ldd produces correct output for an
   executable compiled with i386-uclibc-linux-gcc.
   If this is not the case, reconfigure and rebuild uclibc
   to support ldd.
 - configure and build yaird with uclibc:

	$ ./configure CC=i386-uclibc-linux-gcc \
		--prefix=$HOME/local
	...
	$ make install


Using the application
=====================

See the manual page.


Using yaird as a replacement for mkinitrd
=========================================

If you install a new kernel from your distribution, that means
making a new initial boot image.  The postinstall script that
comes with the kernel will normally do this using mkinitrd;
if you want yaird to be used instead, some tweaking is necessary.

For Debian, there is a native package that includes mkinitrd.yaird,
a wrapper around yaird that uses the same command line conventions
as mkinitrd.  Place the following line in /etc/kernel-img.conf
to use yaird as a replacement for mkinitrd:

	ramdisk = /usr/sbin/mkinitrd.yaird

This only works with kernels distributed after june 2005.

For Fedora, you'll have to modify /sbin/new-kernel-package;
not tested yet.