[PATCH v10 bpf-next 09/10] bpftool: Update doc to describe bpftool btf dump .. format metadata

...and provide an example of output.

Signed-off-by: Alan Maguire <[email protected]>
---
 .../bpf/bpftool/Documentation/bpftool-btf.rst | 28 +++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/tools/bpf/bpftool/Documentation/bpftool-btf.rst b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
index d47dddc2b4ee..1004f9bf0a43 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-btf.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
@@ -28,7 +28,7 @@ BTF COMMANDS
 | **bpftool** **btf help**
 |
 | *BTF_SRC* := { **id** *BTF_ID* | **prog** *PROG* | **map** *MAP* [{**key** | **value** | **kv** | **all**}] | **file** *FILE* }
-| *FORMAT* := { **raw** | **c** [**unsorted**] }
+| *FORMAT* := { **raw** | **c** [**unsorted**] | **meta** }
 | *MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
 | *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* | **name** *PROG_NAME* }
 
@@ -65,7 +65,8 @@ bpftool btf dump *BTF_SRC* [format *FORMAT*] [root_id *ROOT_ID*]
     **format** option can be used to override default (raw) output format. Raw
     (**raw**) or C-syntax (**c**) output formats are supported. With C-style
     formatting, the output is sorted by default. Use the **unsorted** option
-    to avoid sorting the output.
+    to avoid sorting the output.  BTF metadata can be displayed with the
+    **meta** option.
 
     **root_id** option can be used to filter a dump to a single type and all
     its dependent types. It cannot be used with any other types of filtering
@@ -267,3 +268,26 @@ All the standard ways to specify map or program are supported:
   [104859] FUNC 'smbalert_work' type_id=9695 linkage=static
   [104860] FUNC 'smbus_alert' type_id=71367 linkage=static
   [104861] FUNC 'smbus_do_alert' type_id=84827 linkage=static
+
+Display BTF metadata from file vmlinux
+
+**# bpftool btf dump file vmlinux format meta**
+
+::
+
+  size 5161076
+  magic 0xeb9f
+  version 1
+  flags 0x1
+  hdr_len 40
+  type_len 3036368
+  type_off 0
+  str_len 2124588
+  str_off 3036368
+  layout_len 80
+  layout_off 5160956
+  kind 0    UNKNOWN    info_sz 0    elem_sz 0   flags 0
+  kind 1    INT        info_sz 0    elem_sz 0   flags 0
+  kind 2    PTR        info_sz 0    elem_sz 0   flags 0
+  kind 3    ARRAY      info_sz 0    elem_sz 0   flags 0
+  kind 4    STRUCT     info_sz 0    elem_sz 0   flags 0
-- 
2.39.3