[PATCH bpf-next v2] libbpf:Improved usability of the Makefile in libbpf

[Xin Liu]

Current libbpf Makefile does not contain the help command, which
is inconvenient to use. Similar to the Makefile help command of the
perf, a help command is provided to list the commands supported by
libbpf make and the functions of the commands.

Signed-off-by: Xin Liu <liuxin350@xxxxxxxxxx>
---

v2: Simplified display. Some unused commands are displayed in the help command. 

v1: https://lore.kernel.org/bpf/20221129074235.116969-1-liuxin350@xxxxxxxxxx/

 tools/lib/bpf/Makefile | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 4c904ef0b47e..ae523e4cce05 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -286,3 +286,22 @@ tags:
 
 # Delete partially updated (corrupted) files on error
 .DELETE_ON_ERROR:
+
+help:
+	@echo 'libbpf default targets:'
+	@echo '  HINT: use "V=1" to enable verbose build'
+	@echo '  all     - build librarys and pkgconfig'
+	@echo ''
+	@echo 'libbpf install targets:'
+	@echo '  HINT: use "prefix"(default "/usr/local") or "DESTDIR"(default "/")'
+	@echo '        to install to a particular path like "make prefix=/usr/local install"'
+	@echo '  install          - build and install all headers, librarys and pkgconfig'
+	@echo '  install_headers  - install only headers to include/bpf'
+	@echo ''
+	@echo 'libbpf make targets:'
+	@echo '  tags    - use ctags to make tag information for source browsing'
+	@echo '  cscope  - use cscope to make interactive browsing database'
+	@echo ''
+	@echo 'libbpf maintainer targets:'
+	@echo '  clean   - remove all generated files'
+	@echo '  check   - check abi and version info'
-- 
2.33.0