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+\chapter{Machine Configuration Description}
+\label{cfgstr}
+
+RISC-V platforms may contain myriad devices, processor cores, and
+configuration parameters.  To support higher-level software, including
+bootloaders and operating systems, it is recommended that hardware
+platforms embed a description of their components in read-only memory
+that is directly accessible after processor reset for use by low-level
+system software, external debuggers, or manufacturing test procedures.
+We call this low-level embedded information a configuration
+description.  We define here a standard mechanism to encode and locate
+the configuration information, and to determine the format of the
+configuration information.
+
+\section{Configuration String Search Procedure}
+
+The platform must describe how to locate a pointer to find this
+string, for example, by specifying a fixed physical address at which
+the pointer resides.  To support a wide variety of platforms,
+configuration formats, and chips with manufacturing-time programming
+of configuration options, a flexible search procedure is defined to
+locate the configuration information seeded by the initial pointer
+specified by the platform.
+
+The configuration string pointer provided by the platform points to an
+initial memory address at which the search for configuration string
+begins.
+
+The configuration string cannot begin with a padding byte, where a
+padding byte is defined to contain either {\tt 0x0} or {\tt 0xff}, but
+can be preceded by up to 63 padding bytes that are ignored.  If 64
+padding bytes are encountered, then the search terminates without
+finding a config string.
+
+\begin{commentary}
+The padding bytes represent common values returned by unpopulated
+memory or bus regions or unprogrammed non-volatile
+memory. Configuration strings can therefore include pointers to
+regions that are optionally populated or programmed, and these regions
+will be ignored if there is nothing present.  The padding bytes also
+support alignment of binary data structures.
+\end{commentary}
+
+Otherwise the first non-padding byte is the beginning of the
+configuration information.  For example, configuration information in
+Device Tree String format would begin with a ``/dts-v1/''.
+Configuration information in Flattened Device Tree format would begin
+with the magic number {\tt 0xd00dfeed}.  Configuration information in
+the config string format would begin with ``/cs-v1/''.
+\begin{commentary}
+  Config string is a new format that is backwards-compatible with
+  device tree string (as far as DTS specs exist) but can include
+  additional configuration information in other memory regions.
+\end{commentary}
+