update README

README

@@ -8,8 +8,8 @@ recommend to replace a distro's udev installation with the upstream version.
 Tools and rules shipped by udev are not public API and may change at any time.
 Never call any private tool in /lib/udev from any external application, it might
 just go away in the next release. Access to udev information is only offered
-by udevadm and libudev. Tools and rules in /lib/udev and the entire content of
-/dev/.udev/ is private to udev.
+by udevadm and libudev. Tools and rules in /lib/udev, and the entire content of
+the /dev/.udev directory is private to udev and does change whenever needed.
 
 Requirements:
   - Version 2.6.25 of the Linux kernel with sysfs, procfs, signalfd, inotify,
@@ -25,16 +25,16 @@ Requirements:
       CONFIG_INOTIFY=y
       CONFIG_SIGNALFD=y
       CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes)
-      CONFIG_BLK_DEV_BSG=y (SCSI tape devices)
+      CONFIG_BLK_DEV_BSG=y (SCSI devices)
 
-  - For reliable operation, the kernel must not use the CONFIG_SYSFS_DEPRECATED*
+  - For reliable operations, the kernel must not use the CONFIG_SYSFS_DEPRECATED*
     option.
 
-  - Unix domain sockets (CONFIG_UNIX) as a loadable kernel module is not
-    supported.
+  - Unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work,
+    but it is not supported.
 
-  - The proc filesystem must be mounted on /proc/, the sysfs filesystem must
-    be mounted at /sys/. No other locations are supported by udev.
+  - The proc filesystem must be mounted on /proc, the sysfs filesystem must
+    be mounted at /sys. No other locations are supported by udev.
 
   - The system must have the following group names resolvable at udev startup:
       disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, kmem.
@@ -47,29 +47,30 @@ Requirements:
     --disable-extras option.
 
 Operation:
-  Udev creates and removes device nodes in /dev/, based on events the kernel
+  Udev creates and removes device nodes in /dev, based on events the kernel
   sends out on device discovery or removal.
 
-  - Early in the boot process, the /dev/ directory should get a 'tmpfs'
+  - Early in the boot process, the /dev directory should get a 'tmpfs'
     filesystem mounted, which is maintained by udev. Created nodes or changed
     permissions will not survive a reboot, which is intentional.
 
-  - The content of /lib/udev/devices/ directory which contains the nodes,
+  - The content of /lib/udev/devices directory which contains the nodes,
     symlinks and directories, which are always expected to be in /dev, should
     be copied over to the tmpfs mounted /dev, to provide the required nodes
     to initialize udev and continue booting.
 
-  - The old hotplug helper /sbin/hotplug should be disabled in the kernel
-    configuration, it is not needed, and may render the system unusable
-    because of a fork-bombing behavior.
+  - The deprecated hotplug helper /sbin/hotplug should be disabled in the
+    kernel configuration, it is not needed today, and may render the system
+    unusable because the kernel may create too many processes in parallel
+    so that the system runs out-of-memory.
 
   - All kernel events are matched against a set of specified rules in
-    /lib/udev/rules.d/ which make it possible to hook into the event
+    /lib/udev/rules.d which make it possible to hook into the event
     processing to load required kernel modules and setup devices. For all
     devices the kernel exports a major/minor number, udev will create a
     device node with the default kernel name, or the one specified by a
     matching udev rule.
 
-Please direct any comment/question/concern to the linux-hotplug mailing list at:
+Please direct any comment/question to the linux-hotplug mailing list at:
   linux-hotplug@vger.kernel.org