[U-Boot] [PATCH] kbuild/makefile: allow building host tools separately

[Alexey Brodkin <Alexey.Brodkin@synopsys.com>]

Sometimes it is required to build only host U-Boot tools without building
U-Boot itself for either board.

For example:
 * In "buildroot" "uboot-tools" could be built for host just to have an ability
   to create uImage.
 * Linux distributions ship "mkimage" utility as a separate substance.

This patch allows building host U-Boot tools separately from U-Boot itself and
what is more important user only needs to have host compiler (gcc).

To build host tools just execute:
=====
make tools HOST_TOOLS_ONLY=yes
=====

Without this patch to generate tools user needs:
 1. Configure any existing board with "make XXX_config"
 2. Execute tools building but still cross-compiler will be invoked and if
    there's no proper cross-compiler in PATH compilation will fail.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Tom Rini <trini@ti.com>
Cc: Simon Glass <sjg@chromium.org>
---
 Kbuild   | 5 +++++
 Makefile | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/Kbuild b/Kbuild
index 1d89761..b5e348d 100644
--- a/Kbuild
+++ b/Kbuild
@@ -4,6 +4,9 @@
 # 1) Generate generic-asm-offsets.h
 # 2) Generate asm-offsets.h
 
+# Don't execute target below if building host tools only
+ifneq ($(HOST_TOOLS_ONLY),yes)
+
 #####
 # 1) Generate generic-asm-offsets.h
 
@@ -85,3 +88,5 @@ $(CPUDIR)/$(SOC)/asm-offsets.s: $(CPUDIR)/$(SOC)/asm-offsets.c FORCE
 
 $(obj)/$(offsets-file): $(CPUDIR)/$(SOC)/asm-offsets.s
 	$(call cmd,offsets)
+
+endif
diff --git a/Makefile b/Makefile
index b795338..2fb8ea1 100644
--- a/Makefile
+++ b/Makefile
@@ -481,9 +481,12 @@ ifeq ($(dot-config),1)
 # load other configuration
 include $(srctree)/config.mk
 
+# Don't check for config.mk presence if building host tools only
+ifneq ($(HOST_TOOLS_ONLY),yes)
 ifeq ($(wildcard include/config.mk),)
 $(error "System not configured - see README")
 endif
+endif
 
 # If board code explicitly specified LDSCRIPT or CONFIG_SYS_LDSCRIPT, use
 # that (or fail if absent).  Otherwise, search for a linker script in a
@@ -994,10 +997,14 @@ ifeq ($(CONFIG_SYS_GENERIC_BOARD),y)
 	@/bin/false
 endif
 endif
+
+# Don't check for ldscript presence if building host tools only
+ifneq ($(HOST_TOOLS_ONLY),yes)
 ifeq ($(wildcard $(LDSCRIPT)),)
 	@echo >&2 "  Could not find linker script."
 	@/bin/false
 endif
+endif
 
 archprepare: prepare1 scripts_basic
 
-- 
1.8.5.3