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Message-ID: <20080222-114832-init-kconfig-3@tull.net>
Date: Fri, 22 Feb 2008 11:51:20 +1100
From: Nick Andrew <nick@...k-andrew.net>
To: trivial@...nel.org
Cc: linux-kernel@...r.kernel.org, Pavel Emelyanov <xemul@...nvz.org>,
Serge Hallyn <serue@...ibm.com>,
Randy Dunlap <randy.dunlap@...cle.com>,
Paul Menage <menage@...gle.com>, Paul Jackson <pj@....com>,
Valdis Kletnieks <Valdis.Kletnieks@...edu>
Subject: [PATCH 2.6.25-rc2 3/9] Kconfig: Improve init/Kconfig help descriptions - NAMESPACES
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@...k-andrew.net>
---
Try #3.
--- a/init/Kconfig 2008-02-20 09:34:48.000000000 +1100
+++ b/init/Kconfig 2008-02-22 09:01:09.000000000 +1100
@@ -414,31 +414,71 @@ config NAMESPACES
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 (e.g. 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 (e.g. 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 +486,16 @@ config PID_NS
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.
+ This is a function used by container-based virtualisation
+ systems (e.g. vservers). Each process will have a distinct
+ Process ID in each PID namespace which the process is in.
+ Processes in the container are placed in the PID namespace
+ corresponding to the container, and cannot see or affect
+ processes in any parent PID namespace.
+
+ If unsure, say N.
config BLK_DEV_INITRD
bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
--
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