linux-kernel - [PATCH] m32r: Fix endianness constraints

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Date:   Mon, 30 Oct 2017 12:05:05 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Sudip Mukherjee <sudipm.mukherjee@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH] m32r: Fix endianness constraints

The m32r Kconfig provides both CPU_BIG_ENDIAN and CPU_LITTLE_ENDIAN
configuration options.  As they are user-selectable and independent,
this allows invalid configurations:

  - All m32r defconfigs build a big endian kernel, but CPU_BIG_ENDIAN is
    not set, causing compiler warnings like:

	include/linux/byteorder/big_endian.h:7:2: warning: #warning inconsistent configuration, needs CONFIG_CPU_BIG_ENDIAN [-Wcpp]
	 #warning inconsistent configuration, needs CONFIG_CPU_BIG_ENDIAN
	  ^

  - Since commit 5bdfca6435b82944 ("m32r: define CPU_BIG_ENDIAN"),
    building an allmodconfig or allyesconfig enables both
    CONFIG_CPU_BIG_ENDIAN and CONFIG_CPU_LITTLE_ENDIAN.
    While this did get rid of the warning above, both options are
    obviously mutually exclusive.

Fix this by making only CPU_LITTLE_ENDIAN configurable by the user, as
before, and by making sure exactly one of CPU_BIG_ENDIAN and
CPU_LITTLE_ENDIAN is always enabled.

Fixes: 5bdfca6435b82944 ("m32r: define CPU_BIG_ENDIAN")
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
 arch/m32r/Kconfig | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
index 0777f3a8a1f37d6f..6119e04f6bfd7821 100644
--- a/arch/m32r/Kconfig
+++ b/arch/m32r/Kconfig
@@ -195,8 +195,8 @@ config TIMER_DIVIDE
 	default "128"
 
 config CPU_BIG_ENDIAN
-        bool "Generate big endian code"
-	default n
+	bool
+	default !CPU_LITTLE_ENDIAN
 
 config CPU_LITTLE_ENDIAN
         bool "Generate little endian code"
-- 
2.7.4