linux-kernel - [PATCH] xtensa: move CONFIG_CPU_*

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Date:   Sat, 13 Mar 2021 00:14:11 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Chris Zankel <chris@...kel.net>, Max Filippov <jcmvbkbc@...il.com>,
        linux-xtensa@...ux-xtensa.org
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] xtensa: move CONFIG_CPU_*_ENDIAN defines to Kconfig

Move the definition of CONFIG_CPU_*_ENDIAN to Kconfig, the best place
for CONFIG options.

I slightly simplified the test code. You can use the -P option to suppress
linemarker generation. The grep command is unneeded.

  $ echo __XTENSA_EB__ | xtensa-linux-gcc -E -
  # 1 "<stdin>"
  # 1 "<built-in>"
  # 1 "<command-line>"
  # 1 "<stdin>"
  1

  $ echo __XTENSA_EB__ | xtensa-linux-gcc -E -P -
  1

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

If I understood correctly, xtensa compilers can support either
big-endian or little-endian. We cannot change it via a command option.
Actually, it does not understand -mbig-endian or -mlittle-endian.
(Is this correct?)

  $ xtensa-linux-gcc   -mbig-endian  /dev/null  -c -o /dev/null
  xtensa-linux-gcc: error: unrecognized command-line option '-mbig-endian'

I see -mbig-endian / -mlittle-endian in old GCC manual.
  https://gcc.gnu.org/onlinedocs/gcc-3.3.5/gcc/Xtensa-Options.html
But, I cannot see them in recent gcc manuals.
So, I have no idea better than checking __XTENSA_EB__ or __XTENSA_EL__.
I just moved the logic to Kconfig from Makefile.


 arch/xtensa/Kconfig  | 6 ++++++
 arch/xtensa/Makefile | 9 +--------
 2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 9ad6b7b82707..37b04ccc0a7f 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -84,6 +84,12 @@ config KASAN_SHADOW_OFFSET
 	hex
 	default 0x6e400000
 
+config CPU_BIG_ENDIAN
+	def_bool $(success,test "$(shell,echo __XTENSA_EB__ | $(CC) -E -P -)" = 1)
+
+config CPU_LITTLE_ENDIAN
+	def_bool !CPU_BIG_ENDIAN
+
 menu "Processor type and features"
 
 choice
diff --git a/arch/xtensa/Makefile b/arch/xtensa/Makefile
index cf0940708702..f43c731dec89 100644
--- a/arch/xtensa/Makefile
+++ b/arch/xtensa/Makefile
@@ -52,14 +52,7 @@ ifneq ($(CONFIG_LD_NO_RELAX),)
 KBUILD_LDFLAGS := --no-relax
 endif
 
-ifeq ($(shell echo __XTENSA_EB__ | $(CC) -E - | grep -v "\#"),1)
-CHECKFLAGS += -D__XTENSA_EB__
-KBUILD_CPPFLAGS += -DCONFIG_CPU_BIG_ENDIAN
-endif
-ifeq ($(shell echo __XTENSA_EL__ | $(CC) -E - | grep -v "\#"),1)
-CHECKFLAGS += -D__XTENSA_EL__
-KBUILD_CPPFLAGS += -DCONFIG_CPU_LITTLE_ENDIAN
-endif
+CHECKFLAGS += -D $(if $(CONFIG_CPU_BIG_ENDIAN),__XTENSA_EB__,__XTENSA_EL__)
 
 vardirs := $(patsubst %,arch/xtensa/variants/%/,$(variant-y))
 plfdirs := $(patsubst %,arch/xtensa/platforms/%/,$(platform-y))
-- 
2.27.0