Author: bdubbs Date: 2011-03-15 21:16:59 -0600 (Tue, 15 Mar 2011) New Revision: 1120
Added: trunk/boot-cd_easy.txt Log: Add contributed hint Added: trunk/boot-cd_easy.txt =================================================================== --- trunk/boot-cd_easy.txt (rev 0) +++ trunk/boot-cd_easy.txt 2011-03-16 03:16:59 UTC (rev 1120) @@ -0,0 +1,904 @@ +AUTHOR: (original) Thomas Foecking <tho...@foecking.de> and + Christian Hesse <m...@earthworm.de> + (updates) Jimmy Anderson <jimmy.anderson1...@gmail.com> + +DATE: 2011-03-12 + +LICENSE: GNU Free Documentation License Version 1.2 + +SYNOPSIS: Easy Bootable CD of your LFS + + +DESCRIPTION: + +With a little effort, a bootable CD/DVD can be created from an LFS system. +The CD created by this hint could be used as a rescue CD, an LFS build +system, or for whatever other purpose the user can concoct. + +Briefly the bootable CD provides a root filesystem that is +sourced mostly by the (read only) CD contents but with a few +certain directories overlayed by ram and thus writable. + +Briefly, the procedure is: a CD bootloader is +added to the LFS system, a kernel and a ramdisk is created, which +when booted, mounts the LFS system (written on CD) as the root filesystem +and then overlays portions of it with a ram based filesystem which +allows the user to 'write' to some portions of the CD based file system. + +This hint does not create a "live CD". The end result of this hint is a +LFS system that runs off of CD but with only a few directories +being 'writable' by the user and with (except for /tmp) only a +small (few megabytes) amount of writable space. /tmp will be overlayed +by a tmpfs file system and (typically) have 100's of megabytes of space. + +If instead, a live CD is desired, the LFS LiveCD project, or one of +the other Live CD projects may be a more appropriate resource to use. +The value of this 'bootable CD' is that it is simple to do, and +easy to modify and fix. + +The instructions in this hint have been tested with X86 LFS 6.6 & 6.7. +It probably will work with other current LFS books as well. It also +works for building a PowerPC bootable CD. This hint assumes 32bit cpu. + +Note that the instructions in this hint are executed as root. As such, it is +possible that a mistyped or misunderstood instruction could destroy the +data and/or OS on your system. It is prudent to back up any important +data on your system before attempting to use this hint to create a bootable +CD. Ideally, you should perform this task on a system which is only +used by you and which you can easily reinstall without difficulty. That +way, any mistakes you make will not affect others and will have minimal +impact on you. Fair notice... + +ATTACHMENTS: +None + +PREREQUISITES: + +Familiarity with building LFS. The build system must have a writable +CDROM drive and the tool set required to create (mkisofs) ISO images +and write them to CDs. If your system has the 'genisoimage' tool +instead of mkisofs, that will work fine also. + +HINT: + +Contents +-------- + + 1. What do you need and what is the idea? + 2. Configure & compile Kernel, add packages, other tweaks + 3. Add bootloader. + 4. Move /etc /var /root /home to /fake/needwrite and make symlinks + 5. Create boot script which mounts the ramdisk + 6. Tweaks for running with CD as root fs. + 7. Create initial ramdisk + 8. (Optional) compress /usr + 9. Create initial ramdisk + 9a. Burn the Boot CD + 10. Reboot and enjoy + + +1. What do you need and what is the idea? + -------------------------------------- + + What do you need? + + First of all you need to build an LFS system, which you want to burn + on CD. You may want to have a LFS CD for creating new LFS systems + on other computers. Whatever your ideas are, you'll first have to + create this special system on your LFS partition. + (e.g. I have created a LFS system with xfree86 and windowmaker; + now I can boot from CD and create new LFS systems without missing + xfree86 & windowmaker) + + - another linux/unix system to create some stuff and burn the CD + - CD-R(W) drive to burn your LFS system and boot image on CD + - 1 CD-R + 1 CD-RW is very recommended for saving money + + - obtain some additional software: + + (x86) syslinux: (contains isolinux to boot the LFS kernel on CD) +ftp://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-4.03.tar.gz + + (PowerPC) yaboot: (bootloader for PowerPC) +http://yaboot.ozlabs.org/releases/yaboot-1.3.16.tar.gz + + + Download either syslinux (x86) or yaboot (PowerPC) as appropriate + for your architecture and put the source in $LFS/sources for later + use. + + + What is the idea? + - Create kernel with ramdisk and initrd support + - Move /etc /var /root /home to /fake/needwrite + - Set symlinks + /etc -> /fake/needwrite/etc + /var -> /fake/needwrite/var + /... -> /fake/needwrite/... + - Mount /dev/ram0 to /fake/ramdisk + - Copy /fake/needwrite/* to /fake/ramdisk/ + - Remount /dev/ram0 to /fake/needwrite + + We'll have read-write access on /etc /var /root /home + because they point to /fake/needwrite which is then a ramdisk + + You are able to do the most things from the other linux/unix + system by setting LFS to your LFS mountpoint. LFS=/path/to/lfs + e.g.: + +export LFS=/mnt/lfs + + Don't forget to set LFS again when you do a reboot! + + +2. Build LFS system, configure & compile Kernel + -------------------------- + + Do this step in the chroot environment. + + The first step is to build your LFS system as is described in +the LFS book. While in the chroot environment, you will configure & +build the kernel. When configuring your kernel, make sure that the +following kernel configuration settings are enabled +(as builtins, not as modules). + + You need initrd support! + "General setup --->" + "<*> Initial RAM filesystem and RAM disk ..." + + You need ramdisk support! + "Block devices --->" + "<*> RAM block device support" + "(16384) Default RAM disk size" + "[*] Initial RAM disk (initrd) support" + + You need ext2 file system support! + "File systems --->" + "<*> Second extended fs support" + + You need ISO 9660 CDROM file system support! + "File systems --->" + "<*> ISO 9660 CDROM file system support" + +You may need to compress your file system (to fit on CD), and to do so +will need squashfs also. It may not be required but it is best to +just go ahead and enable it anyway while we are building our +kernel to keep things simple. + + (If compressing) You need squashfs file system support! + "File systems --->" + "<*> Squashfs file system support" + + Then compile and install your kernel & modules just +as is described in the LFS book. + + Copy the newly built kernel and associated .config file to /boot: + +cp .config /boot/lfskernel.config +# +# on x86 do: +cp arch/i386/boot/bzImage /boot/lfskernel && cp System.map /boot/ +# +# on a PowerPC do: +cp vmlinux /boot/lfskernel && cp System.map /boot/ + + Set all the configuration settings described in the LFS book +as appropriate for your system. Especially important is that you +set your LFS system root password (or remove it entirely). If +you don't, you will not be able to login when you boot your CD. + + Space will be tight on a CD (not so much on a DVD) so remove any +files and directories that are no longer needed. $LFS/tools +is no longer needed and should be removed. If you won't need the +files in $LFS/sources when running on the CD, some or all of +those can be removed to reduce the size of the image. + + The /usr file system can (optionally) be compressed (later) to free up +space. Compressing it will reduce the size by a couple hundred megabytes +or so. + + Using BLFS (or other techniques) add any additional packages that +you require in your LFS system. + + You will not be able to create directories or files in most portions +of the filesystem so think ahead about what you will need to do +and add whatever directories or files that you might need later when +running on the CD. For example, maybe create /mnt/lfs and it's +associated /tools symlink. + +# +mkdir /mnt/lfs +ln -sv /mnt/lfs/tools / +# + +At this point, it might be wise to save off a copy of your LFS system +in case you screw up and want to start over again at this point. + + +3. Install the bootloader (isolinux or yaboot) + ------------------------------- + + Do this step in the chroot environment. + + We also need a bootloader on the CD to boot the kernel and ramdisk. + + isolinux will be used for the bootloader for X86 machines. + + yaboot will be used for PowerPC MACs. On PowerPC machines + that don't use openfirmware, yaboot is not used and you can skip + building it. For those machines, you will have to figure out the + boot loader installation yourself. + + +# On an X86 machine do: +#------------------- copy and paste ------------------------------ +# +# Unpack, install and configure isolinux +# +cd /sources +zcat syslinux-4.03.tar.gz | tar x +mkdir /isolinux +cp syslinux-4.03/core/isolinux.bin /isolinux/ +rm -fr syslinux-4.03 +# +# If all files associated with the boot process should be in one +# directory we have to move kernel and the Rest of /boot to /isolinux. +# +mv /boot/* /isolinux +# +# Now we create a symlink from boot to isolinux. +# +cd / +rmdir boot +ln -s isolinux boot +# +# Kernel & co can now be found in /boot again. +# But isolinux still needs a config-file, so we create it now: +# +cat > /isolinux/isolinux.cfg << "EOF" +default bootcd +prompt 1 +timeout 40 + +label bootcd + kernel lfskernel + append initrd=initrd.gz root=/dev/ram0 init=/linuxrc ramdisk_size=16384 + +label initrdshell + kernel lfskernel + append initrd=initrd.gz root=/dev/ram0 init=/bin/bash ramdisk_size=16384 +EOF +# +# isolinux is now installed completely. +# +#------------------- end copy and paste --------------------------- + + +# It's a bit more lengthy on a PowerPC machine. Do: +#------------------- copy and paste ------------------------------ +# +mkdir -p /ppc/mac +mkdir -p /ppc/ppc32 +# +# If it isn't already installed, build and install yaboot. +# +cd /sources +tar xvfz yaboot-1.3.16.tar.gz +cd yaboot-1.3.16 +sed -i 's%/usr/local%/usr%' man/* +make PREFIX=/usr +make PREFIX=/usr install +cd .. +cp /usr/lib/yaboot/yaboot /ppc/mac +# +# Create an open firmware configuration file. +# +cat > /ppc/mac/ofboot.b << "EOF" +<CHRP-BOOT> +<COMPATIBLE> +MacRISC MacRISC2 MacRISC3 MacRISC4 +</COMPATIBLE> +<DESCRIPTION> +LFS CD PPC bootloader +</DESCRIPTION> +<BOOT-SCRIPT> +" screen" output +load-base release-load-area +boot cd:,\ppc\mac\yaboot conf=cd:,\ppc\ppc32\yaboot.conf +</BOOT-SCRIPT> +<OS-BADGE-ICONS> +1010 +f8f8f8f8f8f8f8f8f8f8f8f8f8f8f8f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f8f8f8f8f8f8f8f8f8f8f8f8f8f8f8f8 +f8f8f8f8f8f8f8f8f8f8f8f8f8f8f8f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f80000000000000000000000000000f8 +f8f8f8f8f8f8f8f8f8f8f8f8f8f8f8f8 +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +ffffffffffffffffffffffffffffffff +</OS-BADGE-ICONS> +</CHRP-BOOT> +EOF + +# +# Create a yaboot message file +# +cat > /ppc/ppc32/yaboot.msg << "EOF" +MacRISC type machine... +____________________________________________________ + + +GNU/Linux LFS PPC - 32bit + +EOF + +# +# Create a yaboot configuration file. +# +cat > /ppc/ppc32/yaboot.conf << "EOF" +message=/ppc/ppc32/yaboot.msg +delay=20 + +init-message = "\nWelcome to LFS bootCD 2 \nHit <TAB> for boot options.\n\n" +timeout=150 +default=bootcd +#enablecdboot +#enableofboot +#enablenetboot + +image=/boot/lfskernel + label=bootcd + initrd=/boot/initrd.gz + append="rootdelay=2 init=/linuxrc root=/dev/ram0 ramdisk_size=16384" + read-write + pause-after + +image=/boot/lfskernel + label=initrdshell + initrd=/boot/initrd.gz + append="rootdelay=2 init=/bin/bash root=/dev/ram0 ramdisk_size=16384" + read-write + pause-after + +EOF + +# +#------------------- end copy and paste --------------------------- + + + + +4. Move /etc /var /root /home to /fake/needwrite + -------------------------------------------------- + + Do this step in the chroot environment. + + + This step will all directories needing write access to /fake/needwrite + and create symlinks from their original locations. + +#------------------- copy and paste ------------------------------ +# +# move directories +# +mkdir -p /fake/{needwrite,ramdisk} +cd / +mv etc/ var/ root/ home/ fake/needwrite/ +# +# create symlinks so that everything seems to be as before +# +ln -s fake/needwrite/etc etc +ln -s fake/needwrite/var var +ln -s fake/needwrite/root root +ln -s fake/needwrite/home home +ls -l +# +# You should see the following symlinks. +# +# etc -> fake/needwrite/etc +# home -> fake/needwrite/home +# root -> fake/needwrite/root +# var -> fake/needwrite/var +# +#------------------- end copy and paste --------------------------- + + + + +5. Create boot script which mounts the ramdisk + -------------------------------------------- + + Do this step in the chroot environment. + + Ok, we have /etc /var /root /home linked to + /fake/needwrite which is first read-only. + To be able to login (and to run services on runlevel x + which need write access to /etc /var /root or /home) + we must call a script from our /etc/rc.d/init.d/ directory which + creates a ramdisk to /fake/needwrite with write access. + + The following script creates a ramdisk to /fake/ramdisk and + will copy everything of /fake/needwrite to /fake/ramdisk. + Then it remounts the ramdisk to /fake/needwrite. + +#------------------- copy and paste ------------------------------ +# +cat > /etc/rc.d/init.d/create_ramdisk << "EOF" +#!/bin/sh + +dev_ram=/dev/ram0 +dir_ramdisk=/fake/ramdisk +dir_needwrite=/fake/needwrite + +source /etc/rc.d/init.d/functions + +case "$1" in + start) + echo -n "Creating ext2fs on $dev_ram ... " + /sbin/mke2fs -m 0 -i 1024 -q $dev_ram > /dev/null 2>&1 + evaluate_retval + sleep 1 + echo -n "Mounting ramdisk on $dir_ramdisk ... " + mount -n $dev_ram $dir_ramdisk + evaluate_retval + sleep 1 + echo -n "Copying files to ramdisk ... " + cp -dpR $dir_needwrite/* $dir_ramdisk > /dev/null 2>&1 + evaluate_retval + sleep 1 + echo -n "Remount ramdisk to $dir_needwrite ... " + umount -n $dir_ramdisk > /dev/null 2>&1 + sleep 1 + mount -n $dev_ram $dir_needwrite + sleep 1 + ;; + *) + echo "Usage: $0 {start}" + exit 1 + ;; +esac +EOF +chmod 0755 /etc/rc.d/init.d/create_ramdisk +# +# create_ramdisk should be the first script excecuted by init, +# so we set this link: +# /etc/rc.d/rcsysinit.d/S00create_ramdisk -> ../init.d/create_ramdisk +# +cd /etc/rc.d/rcsysinit.d +ln -s ../init.d/create_ramdisk S00create_ramdisk +# +#------------------- end copy and paste --------------------------- + + + + +6. Configure LFS to run from CD + ---------------------- + + Do this step in the chroot environment. + + Since the root filesystem will be mounted from our startup script, +we have to change /etc/fstab of LFS. Delete all entries you don't need. +(e.g. all /dev/hd*) and add /tmp as a tmpfs file system. Also, the +startup scripts need to be tweaked for running on a CD (file systems +don't need to be checked or remounted rw). And since the startup +script runs before the device nodes have been populated, we have to +manually create some device nodes for it. + + +#------------------- copy and paste ------------------------------ +# +cat > /etc/fstab << "EOF" +# Begin /etc/fstab for a bootable CD + +# file system mount-point type options dump fsck +# order +#/dev/EDITME / EDITME defaults 1 1 +#/dev/EDITME swap swap pri=1 0 0 +proc /proc proc defaults 0 0 +sysfs /sys sysfs defaults 0 0 +devpts /dev/pts devpts gid=4,mode=620 0 0 +tmpfs /dev/shm tmpfs defaults 0 0 +tmp /tmp tmpfs defaults 0 0 +# End /etc/fstab +EOF +# +# +# Remove file system check. +# +rm -f /etc/rc.d/rcsysinit.d/S30checkfs +# +# Disable remounting of / as rw in S40mountfs +# +cd /etc/rc.d/init.d +cp -f mountfs origmountfs +grep -v 'remount' origmountfs >mountfs +chmod 0755 mountfs +# +# Ensure that /dev/loop0 exists (compressed /usr requires it). +mknod /lib/udev/devices/loop0 b 7 0 +# +#------------------- end copy and paste --------------------------- + + + +7. Create initial ramdisk + ---------------------- + + If you are chrooted into your LFS system, exit from chroot and return +to your host system. Unmount any virtual file systems that are mounted +into the $LFS tree. + + To ensure that everything is in a good state for the remainder of this +procedure, it may be best to simply shutdown and restart your host system. + + Make sure LFS is set after rebooting!! + +export LFS=/mnt/lfs + +#------------------- copy and paste ------------------------------ +# Add device nodes that will be needed before /dev has been +# populated +# +mknod $LFS/dev/ram0 b 1 0 +# +#------------------- end copy and paste --------------------------- + + Now we create the initrd image file and filesystem. + +#------------------- copy and paste ------------------------------ +# +# +dd if=/dev/zero of=$LFS/boot/initrd bs=1024 count=8192 +mke2fs -m 0 -i 1024 -F $LFS/boot/initrd +# +mount -o loop $LFS/boot/initrd $LFS/mnt +cd $LFS/mnt +mkdir bin lib dev proc mnt +# +mknod $LFS/mnt/dev/ram0 b 1 0 +mknod $LFS/mnt/dev/null c 1 3 +mknod $LFS/mnt/dev/zero c 1 5 +mknod $LFS/mnt/dev/console c 5 1 +mknod $LFS/mnt/dev/ttyS0 c 4 64 +mknod $LFS/mnt/dev/sr0 b 11 0 +mknod $LFS/mnt/dev/sr1 b 11 1 +mknod $LFS/mnt/dev/sda b 8 0 +mknod $LFS/mnt/dev/sdb b 16 0 +mknod $LFS/mnt/dev/sdc b 32 0 +mknod $LFS/mnt/dev/sdd b 48 0 +mknod $LFS/mnt/dev/hda b 3 0 +mknod $LFS/mnt/dev/hdb b 3 64 +mknod $LFS/mnt/dev/hdc b 22 0 +mknod $LFS/mnt/dev/hdd b 22 64 +mknod $LFS/mnt/dev/hde b 33 0 +# +cp $LFS/bin/{bash,mount,grep,umount,echo} $LFS/mnt/bin/ +cp $LFS/usr/bin/test $LFS/mnt/bin/ +cp $LFS/usr/sbin/chroot $LFS/mnt/bin/ +cp $LFS/sbin/pivot_root $LFS/mnt/bin/ +ln -s bash $LFS/mnt/bin/sh +ln -s test $LFS/mnt/bin/[ +# +cp $LFS/lib/{libncursesw.so.5,libdl.so.2,} $LFS/mnt/lib/ +cp $LFS/lib/{libc.so.6,libreadline.so.6} $LFS/mnt/lib/ +cp $LFS/lib/{libhistory.so.6,libblkid.so.1,libuuid.so.1} $LFS/mnt/lib/ +if [ -f $LFS/lib/ld-linux.so.2 ] +then +cp -f $LFS/lib/ld-linux.so.2 $LFS/mnt/lib/ +fi +if [ -f $LFS/lib/ld.so.1 ] +then +cp -f $LFS/lib/ld.so.1 $LFS/mnt/lib/ +fi +# +# +# cat, sleep & mknod are optional, but often useful to have when something +# gos wrong so put them in the initrd also. +# +cp $LFS/bin/{cat,sleep,mknod} $LFS/mnt/bin/ +# +# The first program executed by the kernel is /linuxrc. As it does not +# exist we create it. Our script will find the CD in the correct +# CD-ROM drive and then mount it as rootfs / and run /sbin/init 3. +# +# +cat > $LFS/mnt/linuxrc << "EOF" +#!/bin/sh + + +#ID is the volume id / label of the LFS boot CD that will be looked for. +EOF + +echo "ID=\"LFS_$(date +%Y%m%d)\"" >> $LFS/mnt/linuxrc + +cat >> $LFS/mnt/linuxrc << "EOF" +TMP_MOUNT="/mnt" + +PATH="/bin:/sbin:/usr/bin:/usr/sbin" + +#this script searches for cdrom devices and then tries to find +#the LFS boot CD in order to mount it as / (rootfs) + +#you need following programs: +#- /bin/sh (e.g. bash) +#- echo +#- [ (which is linked to test) +#- mount +#- umount +#- grep +#- pivot_root +#- chroot + +#you need following devices: +#- /dev/hd*, /dev/sd*, /dev/sr* or /dev/cdrom* +#- /dev/null + +#you need following directories: +#- /proc +#- $TMP_MOUNT + +CHECK_TYPE="try_mount" + +if [ ! -d "/proc/" ]; then + mkdir /proc +fi + +mount -n proc /proc -t proc + +#1. Create a list of possible cdrom devices. + +CDROM_LIST="/dev/sr0 /dev/sr1 /dev/cdrom /dev/hda /dev/hdb /dev/hdc /dev/hdd +/dev/hde /dev/sda /dev/sdb" + +#2. now we try to find the LFS boot CD (we use ID as identification) + +LFS_CDROM_DEVICE="" +echo "Using $CHECK_TYPE" +for cdrom_device in $CDROM_LIST +do + echo -n "Checking $cdrom_device ... " + + if [ "$CHECK_TYPE" = "try_mount" ]; then + mount -n -t iso9660 $cdrom_device $TMP_MOUNT > /dev/null 2>&1 + media_found=$? + fi + + if [ $media_found -eq 0 ]; then + + echo -n "media found" + if [ "$CHECK_TYPE" = "try_mount" ]; then + [ -e "$TMP_MOUNT/$ID" ] + media_lfs=$? + fi + + if [ "$CHECK_TYPE" = "try_mount" ]; then + umount -n $cdrom_device > /dev/null 2>&1 + fi + + if [ $media_lfs -eq 0 ]; then + echo ", LFS boot CD found. Ready!" + LFS_CDROM_DEVICE="$cdrom_device" + break; + else + echo ", not LFS boot CD." + fi + + else + echo "no media " + fi +done + + +#3. mount LFS CD as / (root fs) +if [ "$LFS_CDROM_DEVICE" = "" ]; then + + echo "No LFS boot CD found!!! You will have to fix this to continue" + echo "do: mount -n -o ro -t iso9660 'your cd device' $TMP_MOUNT" + echo "Then exit shell to continue" + bash + +else + + echo "Booting from $LFS_CDROM_DEVICE ... " + + mount -n -o ro -t iso9660 $LFS_CDROM_DEVICE $TMP_MOUNT +fi + cd $TMP_MOUNT + pivot_root . mnt + umount -n /mnt/proc >/dev/null 2>&1 + exec chroot . sh -c 'umount -n /mnt >/dev/null 2>&1;\ + exec -a init.new /sbin/init 3'\ + <dev/console >dev/console 2>&1 + +EOF +# +# To make this script executable run +# +chmod 0755 $LFS/mnt/linuxrc +# +# Ok, that's it. Unmount the image and compress it. +# +cd $LFS/ +umount $LFS/mnt +gzip $LFS/boot/initrd +# +#------------------- end copy and paste --------------------------- + + +8) (Optional) compress /usr. + + This step is optional. It's only needed if your media is + too small or if you just want to minimize the size of the ISO + file. + + Before you go further, check the size of your LFS tree: + +du -h $LFS/ + + Verify that it will fit on your media (approx 700MB for a CD..) + + If it will not fit, and there isn't anything that can easily + be removed to make it fit, you can compress the /usr file + system to reduce the size by a couple hundred megabytes. + + To compress your $LFS/usr directory, use mksquashfs to create + a 'squashed' version of $LFS/usr, remove the original $LFS/usr + and modify $LFS/etc/fstab to mount the squashed /usr during + system startup. + + The kernel squashfs support does not universally work with + any squashfs filesystems. Make sure you are using + a version of squashfs tools (likely version 4 or better...) + which creates squashfs files that are compatible with your + kernel. + + chroot is in /usr and must be moved to /sbin if compression + is used. + +#------------------- copy and paste ------------------------------ +mv $LFS/usr/sbin/chroot $LFS/sbin/chroot +mksquashfs $LFS/usr $LFS/usr.sqsh +rm -fr $LFS/usr/* +cat >> $LFS/etc/fstab << "EOF" +/usr.sqsh /usr squashfs loop,ro 0 0 +EOF +#------------------- end copy and paste --------------------------- + + +9. Create Boot CD ISO Image + ---------------- + + If you have a CD-RW you may want to use it for testing. When + your system boots quite good from CD-RW you can burn it on a CD-R. + (I give you this advice, because I got the clue after burning + about 10 CD-Rs that didn't work ;-) + + Because linuxrc must be able to identify the CD you have to create a + file called "LFS_YYYYMMDD". + +#------------------- copy and paste ------------------------------ +touch $LFS/LFS_$(date +%Y%m%d) +#------------------- end copy and paste --------------------------- + + Now create the ISO image of your bootable CD. + +# On a X86 do this: +#------------------- copy and paste ------------------------------ +# +cd $LFS/ +rm -f lfsbootcd.iso +mkisofs -R -l -L -D -b isolinux/isolinux.bin -c isolinux/boot.cat \ +-no-emul-boot -boot-load-size 4 -boot-info-table -V "LFS_$(date +%Y%m%d)" \ +$LFS >lfsbootcd.iso +# +#------------------- end copy and paste --------------------------- + +# On a powerpc do this: +#------------------- copy and paste ------------------------------ +# +# Create a mapping file. +# +cat > $LFS/boot/map.hfs << "EOF" +# ext. xlate creator type comment +.b Raw 'chrp' 'tbxi' "bootstrap" +yaboot Raw 'unix' 'boot' "bootstrap" +.conf Ascii 'unix' 'text' "config" +.msg Ascii 'unix' 'text' "text" +* Raw '????' '????' "unknown" +EOF +# +# +# +rm -f lfsbootcd.iso +mkisofs -r -V "LFS_$(date +%Y%m%d)" -iso-level 4 -chrp-boot -hfs \ +-part -probe -no-desktop \ +-hfs-bless $LFS/ppc/mac -map $LFS/boot/map.hfs \ +-b ppc/mac/yaboot -no-emul-boot \ +-hide-rr-moved -o lfsbootcd.iso $LFS +# +#------------------- end copy and paste --------------------------- + + +9a) Burn the ISO image + + + The ISO image lfsbootcd.iso is complete. Either use your favorite + CD burning tools to burn it or use the cdrecord utility as such: + + Note! + dev=0,0,0 is the device number of your CD-Writer + Check your SCSI devices with "cdrecord -scanbus" + speed=4 should be changed to (max) speed of your CD-Writer. + If you are using a CD-RW add blank=fast to the cdrecord-command! + +cat lfsbootcd.iso |cdrecord -v -eject dev=0,0,0 speed=4 - + + +10. Reboot and enjoy + ---------------- + + Reboot and let your Bios boot from CD. (On PowerPC press the + and hold the 'c' key after reset). + + /tmp will have lots of free space (approx 1/2 of your RAM). + The remaining 'writable' directories (/home and such) will + have about 10meg of free space for you to use. + + Enjoy the kernel messages and login prompt ;-) + +------------------------------------------------------------------ + +ACKNOWLEDGEMENTS: + Special thanks for bug reports and help to: + David Maus <one...@gmx.de> + +CHANGELOG: +[2002-11-19] + * Initial hint. + Thomas Foecking <tho...@foecking.de> + Christian Hesse <m...@earthworm.de> +[2011-03-12] + Updated: Jimmy Anderson <jimmy.anderson1...@gmail.com> + Updated to current LFS, added /usr/compression and + building for PowerPC. Adjusted hint format to template. -- http://linuxfromscratch.org/mailman/listinfo/hints FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
