zdev: Integrate firmware auto-configuration with dracut

Add a dracut hook that applies firmware-provided I/O configuration data
as auto-configuration during boot. This way, all I/O devices configured
by DPM are automatically brought online without further user
interaction.

This mechanism is active by default. It can be deactivated by specifying
the following parameter on the kernel command line:

  rd.zdev=no-auto

Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdev/dracut/95zdev/module-setup.sh

@@ -9,7 +9,8 @@
 # 95zdev/module_setup.sh
 #   This module installs configuration files (udev rules and modprobe.conf
 #   files) required to enable the root device on s390. It will only work when
-#   the root device was configured using the chzdev tool.
+#   the root device was configured using the chzdev tool. In addition,
+#   a hook is installed to parse rd.zdev= kernel parameters.
 #
 
 check() {
@@ -29,15 +30,23 @@ depends() {
 }
 
 installkernel() {
-    local _modules=$(lszdev --by-path / --columns MODULES --no-headings 2>/dev/null)
-
-    [ -z "$_modules" ] && return 0
-    [ ! -z "$_modules" ] && instmods $_modules
+    # Add modules for all device types supported by chzdev (required for
+    # auto-configuration)
+    instmods lcs qeth qeth_l2 qeth_l3 dasd_mod dasd_eckd_mod dasd_fba_mod \
+	     dasd_diag_mod zfcp
 }
 
 install() {
     local _tempfile
 
+    # Ensure that required tools are available
+    inst_multiple chzdev lszdev vmcp
+
+    # Hook to parse zdev kernel parameter
+    inst_hook cmdline 95 "$moddir/parse-zdev.sh"
+
+    # Obtain root device configuration
+
     # Exit early if root device type is unknown
     if ! lszdev --by-path / >/dev/null 2>&1 ; then
         return 0