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Subject[PATCH] Make JFFS2 endianness configurable
Date
This patch allows the endianness of the JFSS2 filesystem to be
specified by config options.

It defaults to native-endian (the previously hard-coded option).

Some architectures benefit from having a single known endianness
of JFFS2 filesystem (for data, not executables) independent of the
endianness of the processor (ARM processors can be switched to either
endianness at run-time).

This patch is taken from:
http://www.infradead.org/pipermail/linux-mtd/2006-January/014717.html

Cc: xe-linux-external@cisco.com
Signed-off-by: Rod Whitby <rod@whitby.id.au>
Signed-off-by: Nikunj Kela <nkela@cisco.com>
---
fs/jffs2/Kconfig | 25 +++++++++++++++++++++++++
fs/jffs2/nodelist.h | 8 +++-----
2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/fs/jffs2/Kconfig b/fs/jffs2/Kconfig
index ad850c5bf2ca..86e93fbc9d74 100644
--- a/fs/jffs2/Kconfig
+++ b/fs/jffs2/Kconfig
@@ -182,3 +182,28 @@ config JFFS2_CMODE_FAVOURLZO
decompression) at the expense of size.

endchoice
+
+choice
+ prompt "JFFS2 endianness"
+ default JFFS2_NATIVE_ENDIAN
+ depends on JFFS2_FS
+ help
+ You can set here the default endianness of JFFS2 from
+ the available options. Do not touch if unsure.
+
+config JFFS2_NATIVE_ENDIAN
+ bool "native endian"
+ help
+ Uses a native endian bytestream.
+
+config JFFS2_BIG_ENDIAN
+ bool "big endian"
+ help
+ Uses a big endian bytestream.
+
+config JFFS2_LITTLE_ENDIAN
+ bool "little endian"
+ help
+ Uses a little endian bytestream.
+
+endchoice
diff --git a/fs/jffs2/nodelist.h b/fs/jffs2/nodelist.h
index 0637271f3770..a1ebf04f217c 100644
--- a/fs/jffs2/nodelist.h
+++ b/fs/jffs2/nodelist.h
@@ -27,12 +27,10 @@
#include "os-linux.h"
#endif

-#define JFFS2_NATIVE_ENDIAN
-
/* Note we handle mode bits conversion from JFFS2 (i.e. Linux) to/from
whatever OS we're actually running on here too. */

-#if defined(JFFS2_NATIVE_ENDIAN)
+#if defined(CONFIG_JFFS2_NATIVE_ENDIAN)
#define cpu_to_je16(x) ((jint16_t){x})
#define cpu_to_je32(x) ((jint32_t){x})
#define cpu_to_jemode(x) ((jmode_t){os_to_jffs2_mode(x)})
@@ -43,7 +41,7 @@
#define je16_to_cpu(x) ((x).v16)
#define je32_to_cpu(x) ((x).v32)
#define jemode_to_cpu(x) (jffs2_to_os_mode((x).m))
-#elif defined(JFFS2_BIG_ENDIAN)
+#elif defined(CONFIG_JFFS2_BIG_ENDIAN)
#define cpu_to_je16(x) ((jint16_t){cpu_to_be16(x)})
#define cpu_to_je32(x) ((jint32_t){cpu_to_be32(x)})
#define cpu_to_jemode(x) ((jmode_t){cpu_to_be32(os_to_jffs2_mode(x))})
@@ -54,7 +52,7 @@
#define je16_to_cpu(x) (be16_to_cpu(x.v16))
#define je32_to_cpu(x) (be32_to_cpu(x.v32))
#define jemode_to_cpu(x) (be32_to_cpu(jffs2_to_os_mode((x).m)))
-#elif defined(JFFS2_LITTLE_ENDIAN)
+#elif defined(CONFIG_JFFS2_LITTLE_ENDIAN)
#define cpu_to_je16(x) ((jint16_t){cpu_to_le16(x)})
#define cpu_to_je32(x) ((jint32_t){cpu_to_le32(x)})
#define cpu_to_jemode(x) ((jmode_t){cpu_to_le32(os_to_jffs2_mode(x))})
--
2.19.1
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