[RFC PATCH 4/6] kbuild: allow linking of an external object into vmlinux

[Andreas Robinson <andr345@gmail.com>]

---
 Makefile |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 22d7584..921d6b4 100644
--- a/Makefile
+++ b/Makefile
@@ -651,7 +651,8 @@ libs-y		:= $(libs-y1) $(libs-y2)
 # Build vmlinux
 # ---------------------------------------------------------------------------
 # vmlinux is built from the objects selected by $(vmlinux-init) and
-# $(vmlinux-main). Most are built-in.o files from top-level directories
+# $(vmlinux-main) and an optional object $(EXTOBJ) specified when
+# running make. Most are built-in.o files from top-level directories
 # in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
 # Ordering when linking is important, and $(vmlinux-init) must be first.
 #
@@ -664,6 +665,8 @@ libs-y		:= $(libs-y1) $(libs-y2)
 #   +--< $(vmlinux-main)
 #   |    +--< driver/built-in.o mm/built-in.o + more
 #   |
+#   +--< $(EXTOBJ) (optional)
+#   |
 #   +-< kallsyms.o (see description in CONFIG_KALLSYMS section)
 #
 # vmlinux version (uname -v) cannot be updated during normal
@@ -686,7 +689,7 @@ export KBUILD_VMLINUX_OBJS := $(vmlinux-all)
 quiet_cmd_vmlinux__ ?= LD      $@
       cmd_vmlinux__ ?= $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) -o $@ \
       -T $(vmlinux-lds) $(vmlinux-init)                          \
-      --start-group $(vmlinux-main) --end-group                  \
+      --start-group $(vmlinux-main) $(EXTOBJ) --end-group        \
       $(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o FORCE ,$^)
 
 # Generate new vmlinux version
-- 
1.5.6.3