Typo

[linux_from_scratch_hints.git] / OLD / uclibc-bootfloppy.txt

TITLE:          uClibc-based bootfloppy
LFS VERSION:    All (tested against LFS-pre4.0)
AUTHOR:         Csaba Henk <ekho@math-inst.hu>

SYNOPSIS: 
        This hints shows a quick and dirty way of creating a
        cutting-edge bootfloppy from scratch, based on uClibc, a
        lightweight C library. "Quick and dirty" means using an ad-hoc,
        non-chroot, but safe development environment. 

VERSION:        0.5

CONTENTS

Introduction
What do we need?
Installing uClibc on the development platform
Setting up the development environment
Creating the root filesystem
Installing uClibc for the bootdisk
Compiling the linux kernel
Installing busybox
Installing gpm
Other programs
Creating the bootdisk
Credits, contributions, bugs and weirdnesses
Appendix A -- the mkbootdisk script

PREFACE

* For the most recent version check out 

http://www.math-inst.hu/~ekho/lowlife/uclibc-bootfloppy.txt

* See changelog at 

http://www.math-inst.hu/~ekho/lowlife/Changelog

* Comments, ideas, critics, flames are welcome.

* (If you are an LFS user, you can skip this.) Although this document is
formally an LFS hint, you can see use of it without knowing what LFS is
(I tried to write it keeping this possibility in mind). Anyway, I
recommend you to check out what LFS is. If you are not familiar with
compiling source code in unix/linux environment, then there is no use of
going on without checking out what LFS is. Consult the following docs
first:

http://www.linuxfromscratch.org/lfs/intro.shtml
http://www.linuxfromscratch.org/faq/
http://www.linuxfromscratch.org/view/4.0/chapter02/chapter02.html

HINT

Introduction
------------

I feel that the bootfloppy created in the BLFS-book is not enough
customized to its task. It uses the system glibc and the system
bootscripts. These are overkill for a bootfloppy. Here we will create a
bootfloppy based on the uClibc C library, which is just made for such
purposes. 

The bootfloppy will be cutting edge: uses uClibc and Busybox which are
actively developed projects for the embedded platform. Moreover, I used
a kernel from the 2.4.* branch (but feel free to use other kernel
releases). It is a good question to ask whether this is useful: many floppy
distros use older kernels for reducing resource usage. I can say the
following: on the one hand, I can afford using a recent kernel as my
bootfloppy merrily runs on my 486 with 8M RAM; on the other hand, from
the moment I began to use this up-to-date stuff, the problems with handling
the terminal buffer and plip timeouts vanished. So unless you are really
tight in resources, I think using a recent kernel is a good idea. 

We will also use some kind of development environment, just to stay on
the safe side.

This hint has a continuation: there we will describe how to install the
svga vncviewer on the bootfloppy, which then becomes capable of turning a
machine to an X terminal. (Check out the svnc-x_terminal hint:

http://hints.linuxfromscratch.org/hints/svnc-x_terminal.txt
http://www.math-inst.hu/~ekho/lowlife/svnc-x_terminal.txt

) 

Additional info and downloadable bootdisk image with svnc can be found
at my homepage (or at its mirror):

http://www.math-inst.hu/~ekho/lowlife/
http://www.personal.ceu.hu/students/01/Csaba_Henk/lowlife/

In this hint the assumption of using an x86 PC (both for making and
booting the floppy) and gcc is set. You may try to port it to another
architecture / compiler. Doing it on another architecture should not
be hard. Doing it with another compiler depends on how much does
uClibc support that compiler.  

If you copy command from this hint to your shell, be careful that
line-terminating backslashes (\) will keep their position (no whitespace
characters should follow them). A possible solution is open this hint in
the Vim GUI, and copy'n'paste from there.

What do we need?
----------------

We will need the following programs; most recent versions are
recommended.

* Addons for the development platform:

sudo (optional)
 ftp://ftp.sudo.ws/pub/sudo/

* Programs for the bootfloppy:

linux kernel 
 http://www.kernel.org
uClibc
 http://www.uclibc.org/downloads/
busybox
 http://www.busybox.net/downloads/
gpm (optional)
 ftp://arcana.linux.it/pub/gpm

Installing uClibc on the development platform
---------------------------------------------

Usually we will optimize to size; in case of uClibc it's done
automatically.

In the uClibc source tree type

make menuconfig

uClibc now has a configuration interface similar to that of the linux
kernel.  Apply the following setting:

Library Installation Options  --->
        (/lib) Shared library loader path 

Apart from this, the default configuration is quite suitable, probably you need
not change anything (especially you need not use full math support). However,
taking a look at the options never hurts; you should make sure that the "Linux
kernel header location" field is filled in correctly (if the kernel release you
use for the floppy is not the same as the one used on the development platform,
you should use the headers of the release used for the floppy), and you may
consider fine-tuning the target processor type. After you exit, 

make &&
make install

Further on we assume that you installed uClibc into
/usr/i386-linux-uclibc/ (the default installation location). 

Setting up the development environment
--------------------------------------

We definitely need some kind of development environment to protect
us from mucking up our system; eg., if we are in the file system
which we will put on the floppy, it is very easy to mistake usr with
/usr, and without such a protection, you can imagine that this
mistake can have serious consequences... 

We will create a non-privileged user named bootdisk for doing the
job. First choose a home directory for bootdisk and store this value
in $BDISKHOME. Then type:

groupadd bootdisk &&
useradd -g bootdisk -s /bin/bash -d $BDISKHOME bootdisk &&
mkdir -p $BDISKHOME &&
cat > $BDISKHOME/.bash_profile << "EOF"
export CFLAGS=-Os
export PATH=/usr/i386-linux-uclibc/bin/:$PATH:$HOME/bin
export CC=i386-uclibc-gcc
EOF

Of course, you may specify more cflags, like -march=i486. The above
setting of the $PATH variable assumes that the usual directories to
be contained in the path are already set in /etc/profile. 

So the idea is that we will work as user bootdisk; however, there are
some tasks during the bootdisk creation which require a privileged user
-- namely, mounting ext2 files and raw-copying to a floppy. 

We can do two things about this problem: 

1) Ignore it, and execute these tasks as root.  

2) Make a script named mkbootdisk for doing this tasks. This script must
be executable only by root (mode 744). With the help of the sudo utility
we let the bootdisk user to use this script as well. That is, we put it
to $BDISKHOME/bin and then type:

echo "
bootdisk ALL = NOPASSWD: $BDISKHOME/bin/mkbootdisk" >> /etc/sudoers
     
A realization of mkbootdisk can be found in Appendix A, or at

http://www.math-inst.hu/~ekho/lowlife/mkbootdisk

Typing "mkbootdisk -h" will print a brief information on usage.

We have the desired environment. We go on compiling the programs. Become
user bootdisk:

su - bootdisk

In the rest of the hint we will act as user bootdisk (except if you
don't use the mkbootdisk script: then the appropriate actions are to be
done as root).

Some of the commands below assume that the actual source archive is
decompressed in $HOME (which is the same as the prior $BDISKHOME). 
Software installation instructions always start at the point when the
source tarball is already decompressed and you entered the source
directory (unless we explicitely claim to act differently).

Creating the root filesystem
-----------------------------------------

We will put the files of the root filesysem of the floppy to a directory
named rfloppy. Firstly we create the directory and a basic tree of
subdirectories which vaguley resembles the FHS idea:

cd &&
mkdir -p rfloppy/{dev,proc,etc/init.d,sbin,bin,lib,mnt,usr,var/log} &&
cat > rfloppy/etc/init.d/rcS << "EOF" &&
#!/bin/sh
mount proc /proc -t proc
EOF

The etc/init.d/rcS file will be the startup script for the floppy. Put
there what you want to be done in the beginnig -- eg., syslogd, klogd,
loading modules, starting gpm, etc.  

A very minimal etc directory is used in this setup. Enriching it (with
files like passwd, group, fstab, modules.conf, and so on) is up to you
-- this minimalist solution works anyway. 

Installing uClibc for the bootdisk 
----------------------------------

We copy the necessary libraries of uClibc to the bootdisk.

cp -a /usr/i386-linux-uclibc/lib/{ld-uClibc*,libc.so.0,libuClibc-*} \
 ~/rfloppy/lib 

Compiling the linux kernel
---------------------------

We will compile a network-aware kernel optimized to size. We don't give
a complete reference, we just highlight some crucial points.If you need
not network-awareness, you may omit TCP/IP netowrking and network
drivers; but even in this case it is strongly recommended to include
"Unix domain sockets". 

In the kernel source tree type:

sed -e 's%-O2%-Os%g' -e '/^CFLAGS_KERNEL/s%\(^.*$\)%\1 -Os%' Makefile > \
 Makefile.tmp &&
mv Makefile.tmp Makefile

The above commands set optimization for size in the Makefile. Edit the
Makefile if you want further optimizations. 

Now you should configure the kernel with "make menuconfig". Choose
carefully the value in the "Processor type and features  --->  Processor
family" meupoint. When choosing options, it is advised to include only
those features you really need. Some important ones:

Networking options  --->
        <*> Unix domain sockets
        [*] TCP/IP networking

In the "Network device support  --->" menupoint choose those network
drivers you intend to use. If you want to use plip, choose it as a
module, and also set:

Parallel port support  --->
        <*> Parallel port support
        <M>   PC-style hardware

This is advised because of the following: as I experienced, if no
option is given, the kernel initializes the parallel port (PC-style)
IRQ-less!  At boot time we won't have the possibility to pass options
to the kernel, as we won't use a boot loader or initrd. Thus we can
set the appropriate IRQ value only if we load the parallel port
driver as module. Also, to gain more control over the NIC drivers,
consider building them as modules.

In this hint we use the devfs facility, so choose 

File systems  --->
        [*] /dev file system support
        [*]   Automatically mount at boot

(See a more detailed description in the devfs hint:

http://hints.linuxfromscratch.org/hints/devfs.txt

). 

And don't forget to include support for the mouse type you will use with
the bootfloppy (if you will use any). 

Now compile the kernel with the 

make dep && make bzImage && make modules

commands. Then type

mkdir $HOME/rfloppy/lib/modules

and copy the NIC driver modules from the drivers/net directory to
$HOME/rfloppy/lib/modules, and also the other modules you built. Eg., if
you use plip, you will need the drivers/parport/parport_pc.o
module.
 
We assume that you do not delete the kernel source. If you do want
to delete it, copy arch/i368/boot/bzImage to a safe place before doing
so.

If you have troubles with configuring the kernel properly, my .config file
might be of your help:

http://www.math-inst.hu/~ekho/lowlife/linux-2.4.19/.config

Installing busybox
------------------

Before making it, adjust the Config.h file according to your needs. To
make busybox work with devfs, be sure that the 

#define BB_FEATURE_DEVFS

line is uncommented (not prefixed with "//"); and it is advised to
enable standard Unix utilities, moreover if you want to use network with
the floppy, consider uncommenting: 

#define BB_IFCONFIG
#define BB_TELNET
#define BB_TFTP
#define BB_FEATURE_IFCONFIG_STATUS

Then install it with

make CROSS=i386-uclibc- &&
make PREFIX=$HOME/rfloppy install

If you have troubles with configuring busybox properly, my Config.h file
might be of your help:

http://www.math-inst.hu/~ekho/lowlife/busybox-0.60.5/Config.h

Installing gpm
--------------

Having mouse at the console is not necessary, but very comfortable for a
bootfloppy as well. If you want it, install gpm by running the following
commands:

export LDFLAGS="-lm" &&
./configure &&
make && 
unset LDFLAGS &&
strip src/gpm &&
mkdir -p $HOME/rfloppy/{usr/sbin,var/run} &&
cp src/gpm $HOME/rfloppy/usr/sbin &&
cp -a /usr/i386-linux-uclibc/lib/{libm-*,libm.so.0} ~/rfloppy/lib

[The /var/run directory is needed for gpm at runtime.]

Other programs
--------------

Now if there is anything more you want to have on the floppy, compile it
and put it to the appropriate place under $HOME/rfloppy. A list of some
possible extensions: 

* devfsd (

http://ftp.kernel.org/pub/linux/daemons/devfsd/

) is not necessary for the bootfloppy, devfs work fine without it. So
install it only if you know what you are doing. However, it needs to be
hacked to get it compiled against uClibc. There is a patch for devfsd at 

http://www.math-inst.hu/~ekho/lowlife/devfsd-1.3.25-uclibc.patch

and you can find some explanation on it at

http://www.math-inst.hu/~ekho/lowlife/

Note that devfsd depends on the libdl.so.0 library of uClibc (which is a
symlink to libdl-0.9.*.so). You have to put these to the /lib of your
filesystem.

* The svnc-x_terminal hint tells you how to compile and install svgalib
and the svga vncviewer to the floppy, giving the bootfloppy the
capabilities of an X terminal.

* You can put tinylogin (

http://tinylogin.busybox.net/

) to the floppy if you want a correct login system on it (with the
configuration described in this hint you just get a prompt after
booting).

* You can put utelnetd ( 

http://www.pengutronix.de/software/utelnetd_en.html

) to the floppy if you want to access it remotely. However, don't forget
that communication is not encrypted under telnet!

* One more useful program is hdparm (

http://ftp.ibiblio.org/pub/Linux/system/hardware

): if you boot with this floppy, the harddisk is probably not used, but
still is a source of noise by its spinning. You can stop it with
hdparm. (See its -y option.)

Creating the bootdisk
---------------------

Put a floppy to the floppy drive. If you use the mkbootdisk script,
check whether the device name of the floppy drive is set correctly in
the script (it is set to /dev/fd0 and no option can change it, in order
to prevent the bootdisk user in being able to muck up the development
platform), and whether the $MKE2FSAPP, $RDEVAPP variables in the script
store the correct path to the mke2fs, rdev utilities in your system
(they should if you follow standards). If everything is fine, simply run 

cd &&
sudo mkbootdisk

If you don't use the mkbootdisk script, become root, store the name of
your floppy device (typically /dev/fd0) in the variable $DISK. Now its
time to find out how big the root filesystem of the floppy should be,
and how much inodes should it have. Concerning the size, I think the
size of the stuff in the rfloppy directory + 150k is enough; concerning
the number of inodes, I think the number of files in rfloppy + 100 is
enough. But you should know. Store the chosen filesystem size in the
variable $SIZE (the number of kilobytes), and the chosen number of
inodes in the variable $INODES. Then type the following:

cd $BDISKHOME &&
# We we create and compress the root filesystem of the floppy:
dd if=/dev/zero of=rootfs bs=1k count=$SIZE &&
yes | mke2fs -m 0 -N $INODES rootfs &&
mkdir -p loop &&
mount rootfs -o loop loop &&
rmdir loop/lost+found &&
cp -a rfloppy/* loop &&
chown -R 0:0 loop/* &&
umount loop &&
dd if=rootfs bs=1k | gzip -v9 > rootfs.gz 

Now check whether rootfs.gz and your kernel image
(linux-2.4.*/arch/i386/boot/bzImage) fit on a floppy together (a floppy
is of 1440k usually but it can be formatted to bigger sizes as well). If
everything is fine, go on:

# We copy the kernel to the floppy:
let KERNELSIZE=`dd bs=1k of=$DISK < linux-2.4.*/arch/i386/boot/bzImage 2>&1 | 
 sed -n '1s%\([0-9][0-9]*\).*%\1%p'`+1 &&
# We perform some adjustments on the kernel copied to the floppy:
rdev $DISK 0,0 &&
rdev -R $DISK 0 &&
rdev -r $DISK `expr 16384 + $KERNELSIZE` &&
# Finally we copy the compressed filesystem to its appropriate place \
# on the floppy:
dd if=rootfs.gz of=$DISK bs=1k seek=$KERNELSIZE

[Explanation -- also for those who wonder how the mkbootdisk script
works

"yes | mke2fs -m 0 -N $INODES rootfs":

This pipe construct is a common trick for answering stupid questions
non-interactively.

"# We copy the kernel to the floppy" :

In the command after this comment we not only copy the kernel to floppy,
but we also store the number of transferred kb's in the variable
$KERNELSIZE.

"# We perform some adjustments on the kernel copied to the floppy" :

We won't have a bootloader to tell the kernel where to find its root
filesystem. The commands after this comment set some specified bits
in the kernel, thus hardwiring the location of the root filesystem to
it: firstly, we tell the kernel to seek for the filesystem in the
floppy, secondly, we tell the kernel that a ramdisk is to be made and
the filesystem is to be decompressed to it, thirdly, we tell the
kernel the location of the filesystem within the floppy. The number
16384 = 2^14 is used for shifting within the range of bits in the
kernel devoted for describing these data. For more information
consult with the Bootdisk HOWTO available at tldp.org. 

"# Finally we copy [...]" :

In the dd command after this comment we use the seek option to copy the
compressed filesystem nicely after the kernel image.]

Now you have the floppy, boot & enjoy! 

Credits, contributions, bugs and weirdnesses
--------------------------------------------

See it in the svnc-x_terminal hint.



* * * Appendices * * *



Appendix A -- the mkbootdisk script
-----------------------------------

If you copy and paste the script below to a separate file, be careful
that line-terminating backslashes (\) will keep their position in the
separate file (no whitespace characters should follow them).

%%%<mkbootdisk>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#!/bin/bash

#
# A script for making the bootdisk creation process easy and safe 
#
# If you develop your own floppy linux, then it is advised to do it as a 
# non-privileged user (in order to not suck if you happen to do
# something  stupid :), and use this (root owned and executable) script
# via the sudo utility. 

# Below are some values set. Adjust them if necessary.


DISK=/dev/fd0
DEVICE="$DISK"
FSDIR=rfloppy
unset FSGZ
KERNEL=linux-`uname -r`/arch/i386/boot/bzImage
TOADD=16384 # Comes from kernel internals, do no change!
MKE2FSAPP=/sbin/mke2fs
RDEVAPP=/usr/sbin/rdev # The $MKE2FSAPP and $RDEVAPP variables contain \
# an absolute path because of the following: \
# by my idea this script is used by a non-privileged user (via sudo) \
# whose path does not contain the mke2fs, rdev executables 
MKBOOTREC="$HOME"/.mkbootdisk
EXTRA_SIZE=150 # Free space left on root filesystem of floppy
EXTRA_INODES=100 # Free inodes left on filesystem of floppy
FLOPPYSIZE=1440
VERSION="0.5"

# Do not edit what follows unless your intention is hacking!

firstcheck=yes  
compress=yes # Any value other than "no" defaults to production of a \
#gzipped rootfs 
KERNELSIZE=x
[ -s "$MKBOOTREC" ] && KERNELSIZE=`cat "$MKBOOTREC"`
dokernelcopy=no # Becomes yes if $KERNELSIZE set to a numerical value
unset TMPDIR
manuallysetkernelsize=no # This variable tracks down whether -r option is used

#
# Usage
#

if [ "$1" = "-h" -o "$1" = "--help" ]; then 
        echo "\
----------------
Bootdisk creation utility, version $VERSION. Usage:
With -h or --help being the 1st arg, this help is shown; otherwise

`basename "$0"` -k kernelimg -f filesys_dir -s filesys_size -i filesys_inodes \\
-r kernelimg_size -c floppy_size [-g gzipped_filesys -d]

where \"kernelimg\" is the linux kernel image to be booted by the floppy,
and \"filesys_dir\" contains the files to be put in the root filesystem.

Default values are: 
-k $KERNEL 
-f $FSDIR 
-s <size of files in filesys_dir + ${EXTRA_SIZE}k> 
-i <number of files in filesys_dir + ${EXTRA_INODES}>
-r \`cat ~/`basename "$MKBOOTREC"`\`, or x if ~/`basename \
"$MKBOOTREC"` is empty or does not exist 
-c $FLOPPYSIZE

Explanations of options:
-r kernelimg_size       a kernelimg of the given size (in kb) is supposed to be
                        on the disk and kernel copying is skipped, unless size 
                        is x instead of a number
-g gzipped_filesys      gzipped_filesys is copied to the disk
                        (instead of the contents of filesys_dir)
-d                      the floppyimage is written to stdout instead of $DISK
-c floppy_size          if the floppy image were bigger than floppy_size 
                        (in kb), the process is aborted, unless floppy_size is 
                        x instead of a number

Further comments:

If kernel is copied and -r was used with a non-numerical value, its size
is stored in ~/`basename "${MKBOOTREC}"` (delete that file before using a
new kernel image, or use -r x !!)

For sake of safety, `basename "$0"` utilizes mktemp; if you don't have it
temporary file creation is still done as safely as it's possible

Example:
* A compressed filesystem is produced from the contents of filesys_dir by
        `basename "$0"` -r 0 -d > rootfs.gz
* A floppy can be made using this compressed filesystem by
        `basename "$0"` -g rootfs.gz
----------------"
        exit 1
fi


#
# Getting options
#

while getopts "g:k:f:dr:c:s:i:" option; do
        case $option in 
                g) FSGZ="$OPTARG"
                   compress=no;;
                k) KERNEL="$OPTARG";;
                f) FSDIR="$OPTARG";;
                d) DEVICE="&1";;
                r) KERNELSIZE="$OPTARG"
                   [ "$OPTARG" -ge 0 ] &>/dev/null && 
                   manuallysetkernelsize=yes;;
                c) FLOPPYSIZE="$OPTARG";;
                i) INODES="$OPTARG";; 
                s) SIZE="$OPTARG";;
                *) exit 1;;
         esac
done




#
# Functions
#

#
# Auxiliary fnc's


# gzipimp -- the concrete way of doing the compression

gzipimp()
{
        dd if=$1 bs=1k | gzip -v9 > $2
        # I could not figure out why it is the way to do gzipping, but this is
        # what is suggested by the clever guys. I'd be happy to be informed
        # about it...
} 

#cleanup -- removes temporary files

cleanup()
{
        [ -e "$TMPDIR" ] && echo "Removing temporary files..." >&2 
        rm -rf "$TMPDIR" >&2 
}

#error -- if something goes wrong... 

error()
{
        echo Error: "$1" >&2
        cleanup
        exit 1
} 

#maketmpdir -- creates a tmp dir as safely as possible

maketmpdir()
{
        if ! TMPDIR=`mktemp -d /tmp/mkbootdisk.$$.XXXXXXXXXX 2>/dev/null`
        then
                TMPDIR=/tmp/mkbootdisk.$$.$RANDOM$RANDOM &&
                rm -rf "$TMPDIR" &&
                mkdir -m 700 "$TMPDIR"
        fi ||
        error "Unable to create temporary directory"     
}

#findoutFSGZ -- finds out the appropriate value of $FSGZ

findoutFSGZ()
{
        [ $compress = yes ] && FSGZ="$TMPDIR"/mkbootdisk-gzipped_fs
}

#
# Important fnc's


# check -- checks the validity of arguments

check()
{
        for v in RDEVAPP MKE2FSAPP; do #Checking whether these apps can be found
                [ -x "`eval echo \\$$v`" ] ||
                error \
"the value of \$$v is wrong -- `eval echo \\$$v` is not an executable"
        done

        for v in SIZE INODES; do # Syntax check of variables
                [ -z "`eval echo \\$$v`" ] ||
                [ "`eval echo \\$$v`" -ge 0 ] &>/dev/null || 
                error \
"wrong value for option -- \$$v is not a non-negative integer"  
        done

        for v in FLOPPYSIZE KERNELSIZE; do 
                [ "`eval echo \\$$v`" = x ] ||
                [ "`eval echo \\$$v`" -ge 0 ] &>/dev/null ||
                error \
"Wrong value for option -- \$$v is neither x, nor non-negative integer"
        done

        if [ "$compress" != no ]; then # checking whether $FSDIR is a directory
                [ "`file -bL "$FSDIR"`" = directory ] ||
                error "$FSDIR is not a directory."
        fi

        if [ $KERNELSIZE = x ]; then #checking whether the kernelimg exists
                [ "`file -bL "$KERNEL"`" = 'x86 boot sector' ] || 
                error "$KERNEL is not a kernelimg." 
        else 
                [ "$firstcheck" = yes ] && 
                echo \
"A kernelimg of size $KERNELSIZE is supposed to be on the disk,
kernel copying is skipped" >&2 
        fi
 
        if [ "$compress" = no ]; then #checking whether the gzipped fs exists
                file -bL "$FSGZ" | grep \
                'gzip compressed data' > /dev/null || 
                error "$FSGZ is not a gzipped file"
                [ "$firstcheck" = yes ] && 
                echo \
"An existing compressed filesystem is used as root filesystem,
filesystem creation is skipped." >&2 
        fi

        firstcheck= 
}

# getfsdata -- Finds out size and inode number param's of the filesystem
# to be created

getfsdata()
{
        if [ $compress = yes ]; then
                [ -z "$SIZE" ] &&
                SIZE=$(expr $EXTRA_SIZE + `du -sD "$FSDIR" | awk '{print $1}'`)
        
                [ -z "$INODES" ] &&
                INODES=$(expr $EXTRA_INODES + `find "$FSDIR" -follow | wc -l`)

        fi
}

# compressfs -- Adjusts and compresses the filesystem
# (Now also creates the filesys but the name is kept)

compressfs()
{
        [ "$compress" = no ] && return 0
        compress=no

        tmpfs="$TMPDIR"/mkbootdisk-rfloppy
        tmpmountpt="$TMPDIR"/mkbootdisk-mountpt
 
        echo \
"Creating an ext2 filesystem of size ${SIZE}k and with $INODES inodes" >&2
        dd if=/dev/zero of="$tmpfs" bs=1k count=$SIZE
        yes | "$MKE2FSAPP" -m 0 -N $INODES "$tmpfs" > /dev/null 
        mkdir -p "$tmpmountpt"
        mount "$tmpfs" -o loop "$tmpmountpt"
        rmdir "$tmpmountpt"/lost+found 
        cp -a "$FSDIR"/* "$tmpmountpt"
        chown -R 0:0 "$tmpmountpt"/*
        if umount "$tmpmountpt"; then
                echo "Compressing the filesystem..." >&2
                gzipimp "$tmpfs" "$FSGZ"
        else
                error "some problem occured with unmounting the file system."
        fi
}


# floppysizecheck -- checks whether will be enough space on floppy

floppysizecheck()
{
        [ $FLOPPYSIZE = x ] && return 0
        FSGZSIZE=$(( `dd if="$FSGZ" of=/dev/null bs=1k 2>&1 |
         sed -n '1s%\([0-9][0-9]*\).*%\1%p'` + 1 ))
        [ $(($KERNELSIZE + $FSGZSIZE)) -gt $FLOPPYSIZE ] &&
        error "
size of kernel:                $KERNELSIZE
size of compressed filesystem: $FSGZSIZE
are altogether:                $KERNELSIZE + $FSGZSIZE = \
$(($KERNELSIZE + $FSGZSIZE))
which exceeds your floppy size ($FLOPPYSIZE)"
}

# kernelcopy -- copies and installs the kernelimg to disk

kernelcopy()
{
        [ $KERNELSIZE = x ] || return 0
 
        tmpdiskimg="$TMPDIR"/mkbootdisk-diskimg 
        echo Copying kernel to diskimage file... >&2
        KERNELSIZE=$(( `dd if="$KERNEL" of="$tmpdiskimg" bs=1k 2>&1 |
         sed -n '1s%\([0-9][0-9]*\).*%\1%p'` + 1 )) ||
        error "cannot create disk image file" 
        echo $(( $KERNELSIZE - 1 ))+1 records in/out >&2
        [ $manuallysetkernelsize = yes ] || echo $KERNELSIZE > "$MKBOOTREC" 

        echo Adjusting the kernelimg to mount the file system as rootfs... >&2 
        "$RDEVAPP" "$tmpdiskimg" 0,0 
        "$RDEVAPP" -R "$tmpdiskimg" 0
        "$RDEVAPP" -r "$tmpdiskimg" `expr $TOADD + $KERNELSIZE`
        dokernelcopy=yes
}

diskwrite()
{
        if [ $dokernelcopy = yes ]; then 
                echo "Completing the diskimage..." >&2
                dd if="$FSGZ" of="$tmpdiskimg" bs=1k seek=$KERNELSIZE 
                echo Writing the diskimage to device... >&2
                eval "dd if=$tmpdiskimg bs=1k >$DEVICE" 
        elif [ $dokernelcopy = no ]; then
                echo Writing the compressed file system to device... >&2
                eval "dd bs=1k seek=$KERNELSIZE >$DEVICE" < "$FSGZ"
        else
                error 'bogus value for $dokernelcopy' 
        fi || 
        error "it seems that there is some problem with the target device."
}


#
# Program body
#

maketmpdir
findoutFSGZ
check
getfsdata
compressfs
kernelcopy
floppysizecheck
check
diskwrite
cleanup
exit 0
%%%</mkbootdisk>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


END of "uClibc-based bootfloppy" hint