[2/2] binman: Support adding sections to FMAPs

diff --git a/tools/binman/entries.rst b/tools/binman/entries.rst
index a91211e93ed..f1c3b7de7ab 100644
--- a/tools/binman/entries.rst
+++ b/tools/binman/entries.rst
@@ -461,8 +461,12 @@  see www.flashrom.org/Flashrom for more information.
 
 When used, this entry will be populated with an FMAP which reflects the
 entries in the current image. Note that any hierarchy is squashed, since
-FMAP does not support this. Also, CBFS entries appear as a single entry -
-the sub-entries are ignored.
+FMAP does not support this. Sections are represented as an area appearing
+before its contents, so that it is possible to reconstruct the hierarchy
+from the FMAP by using the offset information. This convention does not
+seem to be documented, but is used in Chromium OS.
+
+CBFS entries appear as a single entry, i.e. the sub-entries are ignored.
 
 
 
@@ -804,6 +808,11 @@  Properties:
         missing their contents. The second will produce an image but of
         course it will not work.
 
+Properties:
+    _allow_missing: True if this section permits external blobs to be
+        missing their contents. The second will produce an image but of
+        course it will not work.
+
 Since a section is also an entry, it inherits all the properies of entries
 too.
 
diff --git a/tools/binman/etype/fmap.py b/tools/binman/etype/fmap.py
index fe81c6f64a5..fc490292786 100644
--- a/tools/binman/etype/fmap.py
+++ b/tools/binman/etype/fmap.py
@@ -28,8 +28,12 @@  class Entry_fmap(Entry):
 
     When used, this entry will be populated with an FMAP which reflects the
     entries in the current image. Note that any hierarchy is squashed, since
-    FMAP does not support this. Also, CBFS entries appear as a single entry -
-    the sub-entries are ignored.
+    FMAP does not support this. Sections are represented as an area appearing
+    before its contents, so that it is possible to reconstruct the hierarchy
+    from the FMAP by using the offset information. This convention does not
+    seem to be documented, but is used in Chromium OS.
+
+    CBFS entries appear as a single entry, i.e. the sub-entries are ignored.
     """
     def __init__(self, section, etype, node):
         super().__init__(section, etype, node)
@@ -45,6 +49,18 @@  class Entry_fmap(Entry):
             tout.Debug("fmap: Add entry '%s' type '%s' (%s subentries)" %
                        (entry.GetPath(), entry.etype, ToHexSize(entries)))
             if entries and entry.etype != 'cbfs':
+                # Create an area for the section, which encompasses all entries
+                # within it
+                if entry.image_pos is None:
+                    pos = 0
+                else:
+                    pos = entry.image_pos - entry.GetRootSkipAtStart()
+
+                # Drop @ symbols in name
+                name = entry.name.replace('@', '')
+                areas.append(
+                    fmap_util.FmapArea(pos, entry.size or 0,
+                                       tools.FromUnicode(name), 0))
                 for subentry in entries.values():
                     _AddEntries(areas, subentry)
             else:
diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index 217cd0a4249..1f94d99bcfb 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -1594,18 +1594,30 @@  class TestFunctional(unittest.TestCase):
         self.assertEqual(1, fhdr.ver_major)
         self.assertEqual(0, fhdr.ver_minor)
         self.assertEqual(0, fhdr.base)
-        expect_size = fmap_util.FMAP_HEADER_LEN + fmap_util.FMAP_AREA_LEN * 3
+        expect_size = fmap_util.FMAP_HEADER_LEN + fmap_util.FMAP_AREA_LEN * 5
         self.assertEqual(16 + 16 + expect_size, fhdr.image_size)
         self.assertEqual(b'FMAP', fhdr.name)
-        self.assertEqual(3, fhdr.nareas)
+        self.assertEqual(5, fhdr.nareas)
         fiter = iter(fentries)
 
+        fentry = next(fiter)
+        self.assertEqual(b'SECTION0', fentry.name)
+        self.assertEqual(0, fentry.offset)
+        self.assertEqual(16, fentry.size)
+        self.assertEqual(0, fentry.flags)
+
         fentry = next(fiter)
         self.assertEqual(b'RO_U_BOOT', fentry.name)
         self.assertEqual(0, fentry.offset)
         self.assertEqual(4, fentry.size)
         self.assertEqual(0, fentry.flags)
 
+        fentry = next(fiter)
+        self.assertEqual(b'SECTION1', fentry.name)
+        self.assertEqual(16, fentry.offset)
+        self.assertEqual(16, fentry.size)
+        self.assertEqual(0, fentry.flags)
+
         fentry = next(fiter)
         self.assertEqual(b'RW_U_BOOT', fentry.name)
         self.assertEqual(16, fentry.offset)
@@ -2066,8 +2078,8 @@  class TestFunctional(unittest.TestCase):
         self.assertEqual(expected, data[:32])
         fhdr, fentries = fmap_util.DecodeFmap(data[36:])
 
-        self.assertEqual(0x100, fhdr.image_size)
-        expect_size = fmap_util.FMAP_HEADER_LEN + fmap_util.FMAP_AREA_LEN * 3
+        self.assertEqual(0x180, fhdr.image_size)
+        expect_size = fmap_util.FMAP_HEADER_LEN + fmap_util.FMAP_AREA_LEN * 4
         fiter = iter(fentries)
 
         fentry = next(fiter)
@@ -2075,6 +2087,11 @@  class TestFunctional(unittest.TestCase):
         self.assertEqual(0, fentry.offset)
         self.assertEqual(4, fentry.size)
 
+        fentry = next(fiter)
+        self.assertEqual(b'SECTION', fentry.name)
+        self.assertEqual(4, fentry.offset)
+        self.assertEqual(0x20 + expect_size, fentry.size)
+
         fentry = next(fiter)
         self.assertEqual(b'INTEL_MRC', fentry.name)
         self.assertEqual(4, fentry.offset)
diff --git a/tools/binman/test/095_fmap_x86_section.dts b/tools/binman/test/095_fmap_x86_section.dts
index 4cfce456705..fd5f018c923 100644
--- a/tools/binman/test/095_fmap_x86_section.dts
+++ b/tools/binman/test/095_fmap_x86_section.dts
@@ -7,7 +7,7 @@ 
 
 	binman {
 		end-at-4gb;
-		size = <0x100>;
+		size = <0x180>;
 		u-boot {
 		};
 		section {