tools: bpftool: Log info-level messages when building bpftool man pages

To build man pages for bpftool (and for eBPF helper functions), rst2man
can log different levels of information. Let's make it log all levels
to keep the RST files clean.

Doing so, rst2man complains about double colons, used for literal
blocks, that look like underlines for section titles. Let's add the
necessary blank lines.

v2:
- Use "--verbose" instead of "-r 1" (same behaviour but more readable).
- Pass it through a RST2MAN_OPTS variable so we can easily pass other
  options too.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200909162251.15498-2-quentin@isovalent.com

tools/bpf/bpftool/Documentation/Makefile

@@ -28,12 +28,13 @@ man: man8 helpers
 man8: $(DOC_MAN8)
 
 RST2MAN_DEP := $(shell command -v rst2man 2>/dev/null)
+RST2MAN_OPTS += --verbose
 
 $(OUTPUT)%.8: %.rst
 ifndef RST2MAN_DEP
 	$(error "rst2man not found, but required to generate man pages")
 endif
-	$(QUIET_GEN)rst2man $< > $@
+	$(QUIET_GEN)rst2man $(RST2MAN_OPTS) $< > $@
 
 clean: helpers-clean
 	$(call QUIET_CLEAN, Documentation)

tools/bpf/bpftool/Documentation/bpftool-btf.rst

@@ -91,6 +91,7 @@ OPTIONS
 EXAMPLES
 ========
 **# bpftool btf dump id 1226**
+
 ::
 
   [1] PTR '(anon)' type_id=2
@@ -104,6 +105,7 @@ EXAMPLES
 This gives an example of default output for all supported BTF kinds.
 
 **$ cat prog.c**
+
 ::
 
   struct fwd_struct;
@@ -144,6 +146,7 @@ This gives an example of default output for all supported BTF kinds.
   }
 
 **$ bpftool btf dump file prog.o**
+
 ::
 
   [1] PTR '(anon)' type_id=2

tools/bpf/bpftool/Documentation/bpftool-gen.rst

@@ -146,6 +146,7 @@ OPTIONS
 EXAMPLES
 ========
 **$ cat example.c**
+
 ::
 
   #include <stdbool.h>
@@ -187,6 +188,7 @@ This is example BPF application with two BPF programs and a mix of BPF maps
 and global variables.
 
 **$ bpftool gen skeleton example.o**
+
 ::
 
   /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
@@ -241,6 +243,7 @@ and global variables.
   #endif /* __EXAMPLE_SKEL_H__ */
 
 **$ cat example_user.c**
+
 ::
 
   #include "example.skel.h"
@@ -283,6 +286,7 @@ and global variables.
   }
 
 **# ./example_user**
+
 ::
 
   my_map name: my_map

tools/bpf/bpftool/Documentation/bpftool-map.rst

@@ -182,6 +182,7 @@ OPTIONS
 EXAMPLES
 ========
 **# bpftool map show**
+
 ::
 
   10: hash  name some_map  flags 0x0
@@ -203,6 +204,7 @@ The following three commands are equivalent:
 
 
 **# bpftool map dump id 10**
+
 ::
 
   key: 00 01 02 03  value: 00 01 02 03 04 05 06 07
@@ -210,6 +212,7 @@ The following three commands are equivalent:
   Found 2 elements
 
 **# bpftool map getnext id 10 key 0 1 2 3**
+
 ::
 
   key: