From a0ced5164a6180de55946565fb4a7237948c93bb Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Thu, 16 Apr 2015 12:18:26 +0000
Subject: [PATCH] build: tell users to do non-paralle builds on errors

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 45457
---
 include/toplevel.mk | 7 ++++++-
 include/verbose.mk  | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/toplevel.mk b/include/toplevel.mk
index 33baa86da9..d8651d923b 100644
--- a/include/toplevel.mk
+++ b/include/toplevel.mk
@@ -166,6 +166,8 @@ clean dirclean: .config
 prereq:: prepare-tmpinfo .config
 	@+$(NO_TRACE_MAKE) -r -s $@
 
+WARN_PARALLEL_ERROR = $(if $(BUILD_LOG),,$(and $(filter -j,$(MAKEFLAGS)),$(findstring s,$(OPENWRT_VERBOSE))))
+
 ifeq ($(SDK),1)
 
 %::
@@ -184,7 +186,10 @@ else
 			printf "$(_R)WARNING: your configuration is out of sync. Please run make menuconfig, oldconfig or defconfig!$(_N)\n" >&2; \
 		fi \
 	)
-	@+$(ULIMIT_FIX) $(SUBMAKE) -r $@
+	@+$(ULIMIT_FIX) $(SUBMAKE) -r $@ $(if $(WARN_PARALLEL_ERROR), || { \
+		printf "$(_R)Build failed - please re-run with -j1 to see the real error message$(_N)\n" >&2; \
+		false; \
+	} )
 
 endif
 
diff --git a/include/verbose.mk b/include/verbose.mk
index 90aab4c2f5..b7e43f7430 100644
--- a/include/verbose.mk
+++ b/include/verbose.mk
@@ -54,7 +54,7 @@ ifeq ($(findstring s,$(OPENWRT_VERBOSE)),)
   else
     SILENT:=>/dev/null $(if $(findstring w,$(OPENWRT_VERBOSE)),,2>&1)
     export QUIET:=1
-    SUBMAKE=cmd() { $(SILENT) $(MAKE) -s $$* < /dev/null || { echo "make $$*: build failed. Please re-run make with V=s to see what's going on"; false; } } 8>&1 9>&2; cmd
+    SUBMAKE=cmd() { $(SILENT) $(MAKE) -s $$* < /dev/null || { echo "make $$*: build failed. Please re-run make with -j1 V=s to see what's going on"; false; } } 8>&1 9>&2; cmd
   endif
 
   .SILENT: $(MAKECMDGOALS)