Add README for the settings manager

Change-Id: Ia151903e6882d68b7c6d67d39e6634951bd63d7d
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/README-settings-manager.md b/README-settings-manager.md
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+## Introduction
+
+The settings manager has the following design goals:
+
+* Each setting should be a distinct d-bus object.
+
+* The above makes it possible to not even create settings objects that do not
+  apply to a specific system.
+
+* It should be possible, for example, for host0/ and host1/ on a system with
+  two hosts to not only have different values for certain settings, but
+  have different applicable settings as well.
+
+* It should be possible to specify default settings for a system at build-time,
+  based on which the settings manager should at run-time create appopriate
+  d-bus objects and place them on the bus.
+
+## Settings policy file
+
+Some of the design goals above are achieved via a policy file, which is written
+in YAML. Based on this policy file, the settings manager code is generated to be
+able to create only relevant settings d-bus objects along with specifying their
+defaults.
+
+Here's an example of how entries in the YAML would look:
+
+```
+/xyz/openbmc_project/control/host0/boot_mode:
+    Interface: xyz.openbmc_project.Control.Boot.Mode
+    Defaults:
+        BootMode: Mode::Modes::Regular
+
+/xyz/openbmc_project/control/host1/boot_mode:
+    Interface: xyz.openbmc_project.Control.Boot.Mode
+    Defaults:
+        BootMode: Mode::Modes::Safe
+```
+
+It is possible to specify this policy file via a bitbake recipe for a system
+specific policy.