[PATCH 02/46] kbuild: pass jobserver to cmd_ld_vmlinux.o

[Jiri Slaby (SUSE)]

From: Jiri Slaby <jslaby@xxxxxxx>

Until the link-vmlinux.sh split (cf. the commit below), the linker was
run with jobserver set in MAKEFLAGS. After the split, the command in
Makefile.vmlinux_o is not prefixed by "+" anymore, so this information
is lost.

Restore it as linkers working in parallel (namely gcc LTO) make a use of
it. Actually, they complain, if jobserver is not set:
  lto-wrapper: warning: jobserver is not available: '--jobserver-auth=' is not present in 'MAKEFLAGS'

Fixes: 5d45950dfbb1 (kbuild: move vmlinux.o link to scripts/Makefile.vmlinux_o)
Cc: Sedat Dilek <sedat.dilek@xxxxxxxxx>
Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Cc: Michal Marek <michal.lkml@xxxxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Martin Liska <mliska@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 scripts/Makefile.vmlinux_o | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o
index 0edfdb40364b..1c86895cfcf8 100644
--- a/scripts/Makefile.vmlinux_o
+++ b/scripts/Makefile.vmlinux_o
@@ -58,7 +58,7 @@ define rule_ld_vmlinux.o
 endef
 
 vmlinux.o: $(initcalls-lds) vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
-	$(call if_changed_rule,ld_vmlinux.o)
+	+$(call if_changed_rule,ld_vmlinux.o)
 
 targets += vmlinux.o
 
-- 
2.38.1