[PATCH 2.6.25-rc2 3/9] config: Improve init/Kconfig help descriptions - namespaces

[Nick Andrew]

Rewrite the help descriptions for clarity, accuracy and consistency.

Kernel config options affected:

  - NAMESPACES
  - UTS_NS
  - IPC_NS
  - USER_NS
  - PID_NS

Signed-off-by: Nick Andrew <nick@xxxxxxxxxxxxxxx>
---
Here's try #2 at the 3rd patch in the series, for namespace
descriptions. Patching against Linus' git tree now, and trying
to comply with the standards for submitting patches. Each of
the UTS/IPC/USER/PID descriptions is subtly different, but I
hope they all are clear and accurate.


--- a/init/Kconfig	2008-02-20 09:34:48.000000000 +1100
+++ b/init/Kconfig	2008-02-20 22:55:41.000000000 +1100
@@ -414,31 +414,71 @@
 	bool "Namespaces support" if EMBEDDED
 	default !EMBEDDED
 	help
-	  Provides the way to make tasks work with different objects using
-	  the same id. For example same IPC id may refer to different objects
-	  or same user id or pid may refer to different tasks when used in
-	  different namespaces.
+	  Select various namespace options.
+
+	  Namespaces allow different kernel objects (such as processes
+	  or sockets) to have the same ID in different namespaces.
+	  Identifiers like process IDs, which historically were globally
+	  unique, will now be unique only within each PID namespace.
+	  Each task can refer only to PIDs within the same namespace
+	  as the task itself.
+
+	  Namespaces are used by container systems (i.e. vservers)
+	  to provide isolation between the containers.
+
+	  This option does not affect any kernel code directly; it merely
+	  allows you to select namespace options below.
+
+	  Answer Y if you will be using a container system, and you
+	  will probably want to enable all the namespace options
+	  below.
 
 config UTS_NS
 	bool "UTS namespace"
 	depends on NAMESPACES
 	help
-	  In this namespace tasks see different info provided with the
-	  uname() system call
+	  Enable support for multiple UTS system attributes.
+
+	  Each UTS namespace provides an individual view of the
+	  information returned by the uname() system call including
+	  hostname, kernel version and domain name.
+
+	  This is used by container systems (i.e. vservers) so that
+	  each container has its own hostname and other attributes.
+	  Tasks in the container are placed in the UTS namespace
+	  corresponding to the container.
+
+	  Answer Y if you will be using a container system.
 
 config IPC_NS
 	bool "IPC namespace"
 	depends on NAMESPACES && SYSVIPC
 	help
-	  In this namespace tasks work with IPC ids which correspond to
-	  different IPC objects in different namespaces
+	  Enable support for namespace-specific IPC IDs.
+
+	  IPC IDs will be unique only within each IPC namespace.
+
+	  This is used by container systems (i.e. vservers).
+	  Tasks in the container are placed in the IPC namespace
+	  corresponding to the container.
+
+	  Answer Y if you will be using a container system.
 
 config USER_NS
 	bool "User namespace (EXPERIMENTAL)"
 	depends on NAMESPACES && EXPERIMENTAL
 	help
-	  This allows containers, i.e. vservers, to use user namespaces
-	  to provide different user info for different servers.
+	  Enable experimental support for user namespaces.
+
+	  This is a function used by container-based virtualisation systems
+	  (e.g. vservers). User namespaces are intended to ensure that
+	  processes with the same uid which are in different containers are
+	  isolated from each other.
+
+	  Currently user namespaces provide separate accounting, while
+	  isolation must be provided using SELinux or a custom security
+	  module.
+
 	  If unsure, say N.
 
 config PID_NS
@@ -446,12 +486,20 @@
 	default n
 	depends on NAMESPACES && EXPERIMENTAL
 	help
-	  Suport process id namespaces.  This allows having multiple
-	  process with the same pid as long as they are in different
-	  pid namespaces.  This is a building block of containers.
+	  Enable experimental support for hierarchical process id namespaces.
 
-	  Unless you want to work with an experimental feature
-	  say N here.
+	  Process IDs will be unique only within each PID namespace.
+	  This allows multiple processes to have the same PID
+	  so long as they are in different PID namespaces. Furthermore,
+	  each process will have a distinct PID in each namespace
+	  the process is in.
+
+	  This is used by container systems (i.e. vservers).
+	  Tasks in the container are placed in the PID namespace
+	  corresponding to the container, and can only see or
+	  affect processes in the same PID namespace.
+
+	  If unsure, say N.
 
 config BLK_DEV_INITRD
 	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
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