implement /proc hotplugger

README.md

@@ -25,7 +25,7 @@ Dependencies
   - Optional
 * `blkid`
   - Required for UUID, LABEL, PARTUUID support
-* `mdev` OR `mdevd` OR `eudev` OR `systemd-udevd`
+* `mdev` OR `mdevd` OR `eudev` OR `systemd-udevd` OR CONFIG_UEVENT_HELPER
   - systemd-udevd not tested
 * `lvm2`
   - Required for LVM support

config

@@ -46,7 +46,10 @@
 #root_opts=""
 
 # device manager
-# supported - udev, mdev, mdevd
+#
+# supported - none, proc, udev, mdev, mdevd
+# none means no device manager. requires monolithic kernel and you will unable to use UUID, LABEL, PARTUUID, /dev/mapper/*
+# proc requires monolithic kernel and legacy CONFIG_UEVENT_HELPER
 #
 #devmgr=""
 

init

@@ -91,6 +91,16 @@ setup_devmgr()
     [ "$break" = devmgr ] && { print "break before setup_devmgr()"; sh; }
 
     case "$devmgr" in
+        proc)
+            command -v device-helper > /proc/sys/kernel/hotplug
+
+            # get ready for fork bomb. kek
+            find /sys/devices -name uevent |
+
+            while read -r uevent; do
+                printf add > "$uevent"
+            done
+        ;;
         udev)
             udevd -N never & devmgr_pid="$!"
             udevadm trigger -c add -t subsystems
@@ -133,7 +143,9 @@ boot_system()
 {
     [ "$break" = boot ] && { print "break before boot_system()"; sh; }
 
-    kill "$devmgr_pid"
+    {
+        kill "$devmgr_pid" || printf '\n' > /proc/sys/kernel/hotplug
+    } 2> /dev/null || :
 
     # temporary workaround until util-linux release a new version
     # see https://github.com/karelzak/util-linux/issues/997

tinyramfs

@@ -364,9 +364,8 @@ copy_devmgr()
     # false positive
     # shellcheck disable=2016
     case "$devmgr" in
-        none)
-            # TODO implement mode without device manager using deprecated
-            # /sys/kernel/uevent_helper or /proc/sys/kernel/hotplug
+        proc)
+            copy_binary find
         ;;
         mdev)
             for _binary in mdev find; do