[PATCH v1 3/7] DCE/DSE: Add a new scripts/Makefile.syscalls

[Zhangjin Wu]

When CONFIG_TRIM_UNUSED_SYSCALLS is enabled, get used syscalls from
CONFIG_USED_SYSCALLS. CONFIG_USED_SYSCALLS may be a list of used
syscalls or a file to store such a list.

If CONFIG_USED_SYSCALLS is configured as a list of the used syscalls,
directly record them in a used_syscalls variable, if it is a file to
store the list, record the file name to the used_syscalls_file variable
and put its content to the used_syscalls variable.

Signed-off-by: Zhangjin Wu <falcon at tinylab.org>
---
 scripts/Makefile.syscalls | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 scripts/Makefile.syscalls

diff --git a/scripts/Makefile.syscalls b/scripts/Makefile.syscalls
new file mode 100644
index 000000000000..5864d3a85996
--- /dev/null
+++ b/scripts/Makefile.syscalls
@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0
+
+ifndef SCRIPTS_MAKEFILE_SYSCALLS
+  SCRIPTS_MAKEFILE_SYSCALLS = 1
+
+  ifdef CONFIG_TRIM_UNUSED_SYSCALLS
+    ifneq ($(wildcard $(CONFIG_USED_SYSCALLS)),)
+      used_syscalls_file = $(CONFIG_USED_SYSCALLS)
+      ifeq ($(shell test -s $(used_syscalls_file); echo $$?),0)
+        used_syscalls != cat $(CONFIG_USED_SYSCALLS)
+      endif
+    else
+      ifeq ($(subst /,,$(CONFIG_USED_SYSCALLS)),$(CONFIG_USED_SYSCALLS))
+        used_syscalls = $(CONFIG_USED_SYSCALLS)
+      else
+        $(error No such file: $(CONFIG_USED_SYSCALLS))
+      endif
+    endif
+
+    ifneq ($(used_syscalls),)
+      used_syscalls := $(subst $(space),|,$(strip $(used_syscalls)))
+    endif
+
+    used_syscalls_deps = $(used_syscalls_file) $(objtree)/.config
+
+    export used_syscalls used_syscalls_deps
+  endif # CONFIG_TRIM_UNUSED_SYSCALLS
+
+endif # SCRIPTS_MAKEFILE_SYSCALLS
-- 
2.25.1