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Usually, to boot Linux we must define a kernel image and a mount point for root "/". At boot time, if kernel not syncing root partition, often we can have a "kernel panic". With ramusb.igz we can avoid this error, because this system performs several tries to mount root partition and, if boot will fail, open a text console. Ramusb.igz can also boot USB stick or other removable media.
init in ramusb.igz works with principle of "Signature File", in other words search a file inside all disks. File name is user defined; these are the operations:
To boot properly you must set a signature file (i.e "touch /etc/mySlack13.1") and pass this file name as kernel command line in lilo.conf. Example of lilo.conf:
image = /boot/vmlinuz-huge-smp-2.6.xx.x-smp label = myUSBSlack initrd=/boot/ramusb.igz read-only append = "USB_DISK_SIGNATURE=etc/mySlack13.1"
In latest Slackware, kernel works fine with /dev/root device, so fstab may contain only a line:
/dev/root / auto defaults 1 1
The script to build ramusb.igz run in Slackware and creates files using /usr/share/mkinitrd/initrd-tree.tar.gz as base system (Note: it build a 64bit system if you work in Slackware64)
Latest version is 0.7.1 Changelog:
0.6
makeramusb-slack.sh rev. 0.7.1
#!/bin/sh # *** Makeramusb-slack *** copyleft (!C) FZ # *** rev 0.7 04/09/2011 echo "Removing previous structure and files ..." #-------------------------------------------------------- rm -Rf work rm -Rf initrd-tree echo "Getting mkinitrd busybox ..." #-------------------------------------------------------- if [ ! -f ./initrd-tree.tar.gz ] ; then cp -f /usr/share/mkinitrd/initrd-tree.tar.gz . fi if [ -f ./initrd-tree.tar.gz ] ; then mkdir -p initrd-tree tar -C initrd-tree -xzplf initrd-tree.tar.gz else echo " ./initrd-tree.tar.gz not found /usr/share/mkinitrd/initrd-tree.tar.gz not found get and install mkinitrd package ... exit " exit fi echo "Creating the folder structure ..." #-------------------------------------------------------- mkdir -p work/initramfs/{dev,bin,sbin,lib,etc,proc,sys,newroot,usr,usr/bin,usr/sbin} #Create device nodes mknod work/initramfs/dev/null c 1 3 mknod work/initramfs/dev/tty c 5 0 mknod work/initramfs/dev/console c 5 1 cp -f ./initrd-tree/bin/busybox ./work/initramfs/bin/ #Check if busybox is a static binary LIBLIST=`ldd ./work/initramfs/bin/busybox | grep /lib | cut -d'/' -f3 | cut -d'(' -f1 | cut -d' ' -f1` if [ "a$LIBLIST" != "a" ] ; then IFS= echo $LIBLIST | while read LIBNAME do #Copy libs if busybox not static cp -f /lib/$LIBNAME ./work/initramfs/lib/ done fi cd work touch initramfs/etc/mdev.conf chmod +x initramfs/bin/busybox ln -s busybox initramfs/bin/sh echo "Creating a init script" #-------------------------------------------------------- echo '#!/bin/sh export PATH=/bin:/sbin:/usr/bin:/usr/sbin #Mount things needed by this script busybox mount -t proc proc /proc busybox mount -t sysfs sysfs /sys #Create all the symlinks to /bin/busybox /bin/busybox --install -s touch /etc/mtab #Disable kernel messages from popping onto the screen echo 0 > /proc/sys/kernel/printk #Clear the screen clear echo echo echo "------------------------------------" echo " **** RamUSB Boot v 0.7.1 **** " echo "------------------------------------" echo echo /bin/mdev > /proc/sys/kernel/hotplug #Scan for devices mdev -s #Defaults init="/sbin/init" root="/dev/sda1" HD_FOUND= #Get USB-disk SIGNATURE USB_LABEL= COMMAND_LINE=`cat /proc/cmdline` #adjust command line, remove white spaces, etc. COMMAND_LINE=`echo $COMMAND_LINE | sed s/\s+//` COMMAND_LINE=`echo $COMMAND_LINE | sed "s/ =/=/g"` COMMAND_LINE=`echo $COMMAND_LINE | sed "s/= /=/g"` R_RW_OPT="-r" FS_TYPE="" ROOTDEV="" #Parse 12 option parameters #------------------------------------------------ for i in 1 2 3 4 5 6 7 8 9 10 11 12 do OPTION=`echo "$COMMAND_LINE" | cut -d" " -f$i` PARAM=`echo "$OPTION" | cut -d"=" -f1` VALUE=`echo "$OPTION" | cut -d"=" -f2` #Test ro|rw mount option case "$OPTION" in "ro" | "read-only") R_RW_OPT="-r";; "rw" | "read-write") R_RW_OPT="-w";; esac #Test fs type if [ "a$PARAM" = "arootfstype" ] ; then FS_TYPE="-t $VALUE" fi #Test root device if [ "a$PARAM" = "aroot" ] ; then ROOTDEV="$VALUE" fi if [ "a$PARAM" = "aUSB_DISK_SIGNATURE" ] ; then USB_LABEL=$VALUE fi done export R_RW_OPT=$R_RW_OPT export FS_TYPE=$FS_TYPE export ROOTDEV=$ROOTDEV export IFS=`echo -ne " \t\n"` #Search for disk signature in HDs #------------------------------------------------ if [ "a$USB_LABEL" != "a" ] ; then #Try to mount USB-disk echo -n "Searching disk signature: $USB_LABEL " #Rescan for new devices mdev -s #Try to mount all HD devices #--------------------------------------------- ls -1 /dev/hd* 2> /dev/null | while read TRY_DISK do mount $R_RW_OPT $FS_TYPE $TRY_DISK /newroot 1> /dev/null 2> /dev/null if [ -e /newroot/$USB_LABEL ] ; then echo "$USB_LABEL --> HARD DISK $TRY_DISK found" HD_FOUND="yes" break fi umount $TRY_DISK 2> /dev/null done fi #Search for disk signature in SDs #------------------------------------------------ if [ "a$USB_LABEL" != "a" ] && [ "a$HD_FOUND" = "a" ] ; then #Try to mount USB-disk n=0 #Repeat test 10 times while [ $n -le 9 ] do #Rescan for new devices mdev -s #Try to mount all sd devices #--------------------------------------------- ls -1 /dev/sd* 2> /dev/null | while read TRY_DISK do mount $R_RW_OPT $FS_TYPE $TRY_DISK /newroot 1> /dev/null 2> /dev/null if [ -e /newroot/$USB_LABEL ] ; then echo echo "$USB_LABEL found in --> $TRY_DISK" echo break fi umount $TRY_DISK 2> /dev/null done #--------------------------------------------- if [ -e /newroot/$USB_LABEL ] ; then break fi sleep 1 let n=$n+1 echo -n "." done echo " done." fi IS_ROOT_MOUNTED=`mount | grep /newroot` #Check if root is INIRAMFS system #-------------------------------- IS_INITRAMFS=`echo $ROOTDEV | grep .igz` if [ "a$IS_INITRAMFS" != "a" ] ; then cp /newroot/$USB_LABEL/$ROOTDEV / DEV_MOUNTED=`mount | grep /newroot | cut -d" " -f1` umount /newroot eject $DEV_MOUNTED 2>/dev/null mount -t tmpfs none /newroot cd /newroot gzip -dc ../$ROOTDEV | cpio -idm 2> /dev/null cd / rm -f $ROOTDEV else #Check if device with LABEL is mounted #------------------------------------- if [ "a$USB_LABEL" != "a" ] ; then if [ "a$IS_ROOT_MOUNTED" != "a" ] ; then #try also to mount USB_SIGNATURE_FILE as loop device #--------------------------------------------------- if [ -f /newroot/$USB_LABEL ] ; then mount /newroot/$USB_LABEL /newroot -o loop 1> /dev/null 2> /dev/null fi else echo "Error: disk signature <<$USB_LABEL>> not found !!!" fi fi fi #If nothing mounted try root= parameter #------------------------------------------------ if [ "a$IS_ROOT_MOUNTED" = "a" ] && [ "a$ROOTDEV" != "a" ] ; then echo "Try to mount append device root=$ROOTDEV ..." mount $R_RW_OPT $FS_TYPE $ROOTDEV /newroot 1> /dev/null 2> /dev/null fi IS_ROOT_MOUNTED=`mount | grep /newroot` #If nothing mounted ... ask #------------------------------------------------ if [ "a$IS_ROOT_MOUNTED" = "a" ] ; then echo "Error: root device not mounted ..." echo -n "give me another device to try (ex: /dev/sda1) : " read ALT_DEVICE echo "mount $R_RW_OPT $FS_TYPE $ALT_DEVICE /newroot" mount $R_RW_OPT $FS_TYPE $ALT_DEVICE /newroot 1> /dev/null 2> /dev/null fi #Check if $init exists and is executable #------------------------------------------------ #check if perform chroot to /pathname, before if [ -d /newroot/$USB_LABEL ] && [ -x "/newroot/$USB_LABEL/${init}" ] ; then #Unmount all other mounts so that the ram used by #the initramfs can be cleared after switch_root umount /sys /proc #Switch to the new root and execute init mount -o bind /newroot/$USB_LABEL /newroot exec switch_root /newroot "${init}" fi if [[ -x "/newroot/${init}" ]] ; then #Unmount all other mounts so that the ram used by #the initramfs can be cleared after switch_root umount /sys /proc #Switch to the new root and execute init exec switch_root /newroot "${init}" fi #This will only be run if the exec above failed echo "Failed to switch_root, dropping to a shell" exec sh' > initramfs/init chmod +x initramfs/init echo "Creating the .cpio and .igz ..." #-------------------------------------------------------- cd initramfs find . | cpio -H newc -o > ../ramusb.cpio cd .. cat ramusb.cpio | gzip > ramusb.igz echo "Done."
