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Pocket Linux Guide
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4.3. Construction

Rather than copying files directly to the ramdisk, we can make things easier by setting up a staging area. The staging area will give us room to work without worrying about the space constraints of the ramdisk. It will also provide a way to save our work and make it easier to enhance the rootdisk in later phases of the project.

The staging procedure will work like this:

  1. Create a directory structure as defined in the FHS.

  2. Copy in the files from phase 2's root disk.

  3. Build the new package from source code.

  4. Install files into the correct FHS directories.

  5. Strip the binaries to save space.

  6. Check library dependencies.

  7. Copy to the whole directory structure to the ramdisk.

  8. Compress the ramdisk and write it out to floppy.

4.3.1. Create a staging area

bash# mkdir ~/staging
bash# cd ~/staging
bash# mkdir bin boot dev etc home lib mnt opt proc root sbin tmp usr var
bash# mkdir var/log var/run

4.3.2. Copy contents of phase 2 rootdisk

bash# dd if=~/phase2-image.gz | gunzip -c > /dev/ram7
bash# mount /dev/ram7 /mnt
bash# cp -dpR /mnt/* ~/staging
bash# umount /dev/ram7
bash# rmdir ~/staging/lost+found

4.3.3. Install binaries from GNU coreutils

Download a recent version of coreutils from ftp://ftp.gnu.org/gnu/coreutils/

bash# cd /usr/src/coreutils-5.2.1
bash# export CC="gcc -mcpu=i386"
bash# ./configure --host=i386-pc-linux-gnu
bash# make
bash# cd src
bash# cp cat chgrp chmod chown cp date dd df ~/staging/bin
bash# cp hostname ln ls mkdir mkfifo mknod ~/staging/bin
bash# cp mv rm rmdir stty su sync uname ~/staging/bin

4.3.4. Copy additional libraries

Check library requirements by using ldd on some of the new binaries.

bash# ldd ~/staging/bin/cat
bash# ldd ~/staging/bin/ls
bash# ldd ~/staging/bin/su
bash# ls ~/staging/lib

Note the differences in the required libraries, as shown by the ldd command, and the libraries present in the staging area, as shown by the ls command, then copy any missing libraries to the staging area.

bash# cp /lib/librt.so.1 ~/staging/lib
bash# cp /lib/libpthread.so.0 ~/staging/lib
bash# cp /lib/libcrypt.so.1 ~/staging/lib

4.3.5. Strip binaries and libraries

bash# strip ~/staging/bin/*
bash# strip --strip-unneeded ~/staging/lib/*

4.3.6. Create a compressed root disk image

bash# cd /
bash# dd if=/dev/zero of=/dev/ram7 bs=1k count=4096
bash# mke2fs -m0 /dev/ram7 4096
bash# mount /dev/ram7 /mnt
bash# cp -dpR ~/staging/* /mnt
bash# umount /dev/ram7
bash# dd if=/dev/ram7 of=~/phase3-image bs=1k count=4096
bash# gzip -9 ~/phase3-image

The process for creating the compressed root disk image will change very little throughout the remaining chapters. Writing a small script to handle this function can be a great time saver.

4.3.7. Write the root disk image to floppy

Insert the diskette labeled "root disk" into drive fd0.

bash# dd if=~/phase3-image.gz of=/dev/fd0 bs=1k
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