On Thu, Jun 8, 2017 at 1:07 AM, Babu Moger [off-list ref] wrote:

On 5/29/2017 9:56 PM, Michael Ellerman wrote:

quoted

Geert Uytterhoeven [off-list ref] writes:

quoted

Hi Michael,

On Mon, May 29, 2017 at 2:07 PM, Michael Ellerman [off-list ref]
wrote:

quoted

Geert Uytterhoeven [off-list ref] writes:

quoted

On Tue, May 23, 2017 at 11:45 PM, Babu Moger [off-list ref]
wrote:

quoted

quoted

So far we tried always doing that, but a few checks for the semi-existing
Kconfig symbol crept in in generic code. Those could be replaced by the
__*__
variants, but consistently having the Kconfig symbols would be useful
anyway
(e.g. to avoid building the broken-on-big-endian ISDN drivers).

Ah OK, the original mail was citing C code, but yeah I guess it would be
handy in Makefiles etc.

Thanks for all the responses.  I see couple of options here.

1. Fix the c code in include/asm-generic/qrwlock.h using ifdef
__BIG_ENDIAN__
    This will fix the issue for us.

2. Define CPU_BIG_ENDIAN for all the missing fixed endian architectures.
Because the problem is only for fixed big endian archs.

I prefer the option 1.  What do you guys think ?

I would prefer option 2. If we leave out CONFIG_CPU_LITTLE_ENDIAN,
then the patch becomes much easier than what we had discussed earlier,
and we just need to patch a few Kconfig files to add

config CPU_BIG_ENDIAN
       def_bool y

I would also suggest adding a sanity check like

diff --git a/include/linux/byteorder/big_endian.h

b/include/linux/byteorder/big_endian.h
index 392041475c72..18a1ab5b0260 100644

--- a/include/linux/byteorder/big_endian.h
+++ b/include/linux/byteorder/big_endian.h

@@ -3,5 +3,9 @@

 #include <uapi/linux/byteorder/big_endian.h>

+#ifndef CONFIG_CPU_BIG_ENDIAN
+#warning inconsistent configuration, need CONFIG_CPU_BIG_ENDIAN
+#endif
+
 #include <linux/byteorder/generic.h>
 #endif /* _LINUX_BYTEORDER_BIG_ENDIAN_H */

diff --git a/include/linux/byteorder/little_endian.h

b/include/linux/byteorder/little_endian.h
index 08057377aa23..ba910bb9aad0 100644

--- a/include/linux/byteorder/little_endian.h
+++ b/include/linux/byteorder/little_endian.h

@@ -3,5 +3,9 @@

 #include <uapi/linux/byteorder/little_endian.h>

+#ifdef CONFIG_CPU_BIG_ENDIAN
+#warning inconsistent configuration, CONFIG_CPU_BIG_ENDIAN is set
+#endif
+
 #include <linux/byteorder/generic.h>
 #endif /* _LINUX_BYTEORDER_LITTLE_ENDIAN_H */

Fixing xtensa properly might still be tricky, but with that change, at least
we detect when things go wrong in this area.

        Arnd