initramfs: New modular initramfs for booting kernel from various media.

* Design principles:
* This initramfs just mounts roots and runs init on it, nothing else.
* Whenever possible, existing kernel parameters are used. When extended
  boot methods are provided, new parameters mimick/adhere to existing 
  conventions.
* System is modular/pluggable - each mount method is in own module with
  more or less well defined interface, it's possible to construct complete
  system with any combination of modules.
* Modules includes: initramfs-module-loop, initramfs-module-nfs, to boot
  from loop devices (including recursive loops) and NFS, correspondingly.

1 files changed, 54 insertions, 0 deletions

diff --git a/packages/initrdscripts/files/loopboot.sh b/packages/initrdscripts/files/loopboot.sh
new file mode 100644
index 0000000000..55a1948db8
--- /dev/null
+++ b/packages/initrdscripts/files/loopboot.sh
@@ -0,0 +1,54 @@
+#!/bin/sh
+
+if [ "$ROOT_DEVICE" = "/dev/loop" ]; then
+    loop_mount() {
+        loopdev=/dev/loop$loop_num
+        mountpt=/mnt/loop$loop_num
+
+        [ -e $loopdev ] || mknod $loopdev b 7 $loop_num
+
+        # if only one argument was specified, let it be path not dev
+        if [ -z "$path" ] && [ -n "$dev" ]; then
+            path="$dev"
+            dev=""
+        fi
+        [ -z "$offset" ] && offset=0
+     
+        if [ -n "$dev" ]; then
+            hostpt=`expr "$dev" : '.*/\([^/]*\)'`
+            [ -z "$hostpt" ] && hostpt="$dev"
+            
+            echo "Mounting $dev on $hostpt"
+            mkdir $hostpt
+            mount $dev $hostpt
+            cd $hostpt
+        fi
+    
+        echo "Loopback setup of $path (offset $offset)"
+        losetup -o "$offset" "$loopdev" "$path"
+
+        echo "Mounting $loopdev on $mountpt"
+        mkdir "$mountpt"
+        mount "$loopdev" "$mountpt"
+        cd "$mountpt"
+        BOOT_ROOT="$mountpt"
+        loop_num=`expr "$loop_num" + 1`
+    }
+
+    modprobe vfat
+    modprobe loop
+    
+    loop_num=0
+    
+    for arg in $CMDLINE; do
+        optarg=`expr "x$arg" : 'x[^=]*=\(.*\)'`
+        echo $arg xxx $optarg 
+        case $arg in
+            looproot=*)
+                dev=`expr "$optarg" : '\([^:]*\).*'`
+                path=`expr "$optarg" : '[^:]*:\([^:]*\).*'`
+                offset=`expr "$optarg" : '[^:]*:[^:]*:\([^:]*\).*'`
+                loop_mount ;;
+        esac
+    done
+fi