From 026f9cf24f3c9d30c47c42bac622a64338caf596 Mon Sep 17 00:00:00 2001
From: Masahiro Yamada
Date: Wed, 5 Mar 2014 16:59:40 +0900
Subject: kbuild: improve Kbuild speed

Kbuild brought about many advantages for us but a significant
performance regression was reported by Simon Glass.

After some discussions and analysis, it turned out
its main cause is in $(call cc-option,...).

Historically, U-Boot parses all config.mk
(arch/*/config.mk and board/*/config.mk)
every time descending into subdirectories.
That means cc-options are evaluated over and over again.

$(call cc-option,...) is useful but costly.
So we want to evaluate them only in ./Makefile
and spl/Makefile and export compiler flags.

This commit changes the build system as follows:

  - Modify scripts/Makefile.build to not include config.mk
    Instead, add $(PLATFORM_CPPFLAGS) to asflags-y, ccflags-y,
    cppflags-y.

  - Export many variables
    Going forward, Kbuild will not parse config.mk files
    when it descends into subdirectories.
    If we want to set variables in config.mk and use them
    in subdirectories, they must be exported.

    This is the list of variables to get exported:
      PLATFORM_CPPFLAGS
      CPUDIR
      BOARDDIR
      OBJCOPYFLAGS
      LDFLAGS
      LDFLAGS_FINAL
        (used in nand_spl/board/*/*/Makefile)
      CONFIG_STANDALONE_LOAD_ADDR
        (used in examples/standalone/Makefile)
      SYM_PREFIX
        (used in examples/standalone/Makefile)
      RELFLAGS
        (used in examples/standalone/Makefile)

  - Delete CPPFLAGS
    This variable has been replaced with PLATFORM_CPPFLAGS

  - Copy gcclibdir from example/standalone/Makefile
    to arch/sparc/config.mk
    The reference in CONFIG_STANDALONE_LOAD_ADDR must be
    resolved before it is exported.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Reported-by: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org> [on Sandbox]
Tested-by: Stephen Warren <swarren@nvidia.com> [on Tegra]
---
 Makefile | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

(limited to 'Makefile')

diff --git a/Makefile b/Makefile
index 4e61ae914c8..c03a1b4ac7a 100644
--- a/Makefile
+++ b/Makefile
@@ -358,13 +358,13 @@ UBOOTRELEASE = $(shell cat include/config/uboot.release 2> /dev/null)
 UBOOTVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
 
 export VERSION PATCHLEVEL SUBLEVEL UBOOTRELEASE UBOOTVERSION
-export ARCH CPU BOARD VENDOR SOC
+export ARCH CPU BOARD VENDOR SOC CPUDIR BOARDDIR
 export CONFIG_SHELL HOSTCC HOSTCFLAGS HOSTLDFLAGS CROSS_COMPILE AS LD CC
 export CPP AR NM LDR STRIP OBJCOPY OBJDUMP
 export MAKE AWK
 export DTC CHECK CHECKFLAGS
 
-export KBUILD_CPPFLAGS NOSTDINC_FLAGS UBOOTINCLUDE
+export KBUILD_CPPFLAGS NOSTDINC_FLAGS UBOOTINCLUDE OBJCOPYFLAGS LDFLAGS
 export KBUILD_CFLAGS KBUILD_AFLAGS
 
 # When compiling out-of-tree modules, put MODVERDIR in the module
@@ -567,7 +567,8 @@ NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
 CHECKFLAGS     += $(NOSTDINC_FLAGS)
 
 # FIX ME
-cpp_flags := $(KBUILD_CPPFLAGS) $(CPPFLAGS) $(UBOOTINCLUDE) $(NOSTDINC_FLAGS)
+cpp_flags := $(KBUILD_CPPFLAGS) $(PLATFORM_CPPFLAGS) $(UBOOTINCLUDE) \
+							$(NOSTDINC_FLAGS)
 c_flags := $(KBUILD_CFLAGS) $(cpp_flags)
 
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