dracut: Introduce --force-drivers parameter and force_drivers=+ config option

Index: dracut-037/dracut.sh
===================================================================
@@ -81,6 +81,10 @@ Creates initial ramdisk images for prelo
                          exclusively include in the initramfs.
   --add-drivers [LIST]  Specify a space-separated list of kernel
                          modules to add to the initramfs.
+  --force-drivers [LIST] Specify a space-separated list of kernel
+                         modules to add to the initramfs and make sure they
+                         are tried to be loaded via modprobe same as passing
+                         rd.driver.pre=DRIVER kernel parameter.
   --omit-drivers [LIST] Specify a space-separated list of kernel
                          modules not to add to the initramfs.
   --filesystems [LIST]  Specify a space-separated list of kernel filesystem

@@ -299,6 +303,7 @@ rearrange_params()
         --long add: \
         --long force-add: \
         --long add-drivers: \
+        --long force-drivers: \
         --long omit-drivers: \
         --long modules: \
         --long omit: \

@@ -463,6 +468,7 @@ while :; do
         -a|--add)      push add_dracutmodules_l  "$2"; PARMS_TO_STORE+=" '$2'"; shift;;
         --force-add)   push force_add_dracutmodules_l  "$2"; PARMS_TO_STORE+=" '$2'"; shift;;
         --add-drivers) push add_drivers_l        "$2"; PARMS_TO_STORE+=" '$2'"; shift;;
+        --force-drivers) push force_drivers_l        "$2"; PARMS_TO_STORE+=" '$2'"; shift;;
         --omit-drivers) push omit_drivers_l      "$2"; PARMS_TO_STORE+=" '$2'"; shift;;
         -m|--modules)  push dracutmodules_l      "$2"; PARMS_TO_STORE+=" '$2'"; shift;;
         -o|--omit)     push omit_dracutmodules_l "$2"; PARMS_TO_STORE+=" '$2'"; shift;;

@@ -880,6 +886,13 @@ if (( ${#add_drivers_l[@]} )); then
 fi
 add_drivers=${add_drivers/-/_}
 
+if (( ${#force_drivers_l[@]} )); then
+    while pop force_drivers_l val; do
+        force_drivers+=" $val "
+    done
+fi
+force_drivers=${force_drivers/-/_}
+
 if (( ${#omit_drivers_l[@]} )); then
     while pop omit_drivers_l val; do
         omit_drivers+=" $val "

@@ -896,6 +909,7 @@ fi
 omit_drivers_corrected=""
 for d in $omit_drivers; do
     [[ " $drivers $add_drivers " == *\ $d\ * ]] && continue
+    [[ " $drivers $force_drivers " == *\ $d\ * ]] && continue
     omit_drivers_corrected+="$d|"
 done
 omit_drivers="${omit_drivers_corrected%|}"

@@ -1287,6 +1301,13 @@ if [[ $no_kernel != yes ]]; then
     if [[ $add_drivers ]]; then
         hostonly='' instmods -c $add_drivers
     fi
+    if [[ $force_drivers ]]; then
+        hostonly='' instmods -c $force_drivers
+        rm -f $initdir/etc/cmdline.d/20-force_driver.conf
+        for mod in $force_drivers; do
+            echo "rd.driver.pre=$mod" >>$initdir/etc/cmdline.d/20-force_drivers.conf
+        done
+    fi
     if [[ $filesystems ]]; then
         hostonly='' instmods -c $filesystems
     fi

Index: dracut-037/dracut.8.asc
===================================================================
@@ -136,6 +136,19 @@ example:
 ----
 ===============================
 
+**--force-drivers** _<list of kernel modules>_::
+    See add-drivers above. But in this case it is ensured that the drivers
+    are tried to be loaded early via modprobe.
++
+[NOTE]
+===============================
+If [LIST] has multiple arguments, then you have to put these in quotes. For
+example:
+----
+# dracut --force-drivers "kmodule1 kmodule2"  ...
+----
+===============================
+
 **--omit-drivers** _<list of kernel modules>_::
     specify a space-separated list of kernel modules not to add to the
     initramfs.