docs: early-userspace: convert docs to ReST and rename to *.rst

The two files there describes a Kernel API feature, used to
support early userspace stuff. Prepare for moving them to
the kernel API book by converting to ReST format.

The conversion itself was quite trivial: just add/mark a few
titles as such, add a literal block markup, add a table markup
and a few blank lines, in order to make Sphinx to properly parse it.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

3 files changed, 34 insertions, 6 deletions

diff --git a/Documentation/early-userspace/buffer-format.txt b/Documentation/early-userspace/buffer-format.rst
index e1fd7f9dad16..7f74e301fdf3 100644
--- a/Documentation/early-userspace/buffer-format.txt
+++ b/Documentation/early-userspace/buffer-format.rst
@@ -1,8 +1,10 @@
-		       initramfs buffer format
-		       -----------------------
+=======================
+initramfs buffer format
+=======================
 
-		       Al Viro, H. Peter Anvin
-		      Last revision: 2002-01-13
+Al Viro, H. Peter Anvin
+
+Last revision: 2002-01-13
 
 Starting with kernel 2.5.x, the old "initial ramdisk" protocol is
 getting {replaced/complemented} with the new "initial ramfs"
@@ -18,7 +20,8 @@ archive can be compressed using gzip(1).  One valid version of an
 initramfs buffer is thus a single .cpio.gz file.
 
 The full format of the initramfs buffer is defined by the following
-grammar, where:
+grammar, where::
+
 	*	is used to indicate "0 or more occurrences of"
 	(|)	indicates alternatives
 	+	indicates concatenation
@@ -49,7 +52,9 @@ hexadecimal ASCII numbers fully padded with '0' on the left to the
 full width of the field, for example, the integer 4780 is represented
 by the ASCII string "000012ac"):
 
+============= ================== ==============================================
 Field name    Field size	 Meaning
+============= ================== ==============================================
 c_magic	      6 bytes		 The string "070701" or "070702"
 c_ino	      8 bytes		 File inode number
 c_mode	      8 bytes		 File mode and permissions
@@ -65,6 +70,7 @@ c_rmin	      8 bytes		 Minor part of device node reference
 c_namesize    8 bytes		 Length of filename, including final \0
 c_chksum      8 bytes		 Checksum of data field if c_magic is 070702;
 				 otherwise zero
+============= ================== ==============================================
 
 The c_mode field matches the contents of st_mode returned by stat(2)
 on Linux, and encodes the file type and file permissions.
@@ -82,7 +88,8 @@ If the filename is "TRAILER!!!" this is actually an end-of-archive
 marker; the c_filesize for an end-of-archive marker must be zero.
 
 
-*** Handling of hard links
+Handling of hard links
+======================
 
 When a nondirectory with c_nlink > 1 is seen, the (c_maj,c_min,c_ino)
 tuple is looked up in a tuple buffer.  If not found, it is entered in
diff --git a/Documentation/early-userspace/README b/Documentation/early-userspace/early_userspace_support.rst
index 955d667dc87e..3deefb34046b 100644
--- a/Documentation/early-userspace/README
+++ b/Documentation/early-userspace/early_userspace_support.rst
@@ -1,3 +1,4 @@
+=======================
 Early userspace support
 =======================
 
@@ -26,6 +27,7 @@ archive to be used as the image or have the kernel build process build
 the image from specifications.
 
 CPIO ARCHIVE method
+-------------------
 
 You can create a cpio archive that contains the early userspace image.
 Your cpio archive should be specified in CONFIG_INITRAMFS_SOURCE and it
@@ -34,6 +36,7 @@ CONFIG_INITRAMFS_SOURCE and directory and file names are not allowed in
 combination with a cpio archive.
 
 IMAGE BUILDING method
+---------------------
 
 The kernel build process can also build an early userspace image from
 source parts rather than supplying a cpio archive.  This method provides
diff --git a/Documentation/early-userspace/index.rst b/Documentation/early-userspace/index.rst
new file mode 100644
index 000000000000..2b8eb6132058
--- /dev/null
+++ b/Documentation/early-userspace/index.rst
@@ -0,0 +1,18 @@
+:orphan:
+
+===============
+Early Userspace
+===============
+
+.. toctree::
+    :maxdepth: 1
+
+    early_userspace_support
+    buffer-format
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`