Raise the minimum required gcc version to 4.6
authorJoe Perches <joe@perches.com>
Mon, 20 Aug 2018 20:15:26 +0000 (13:15 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 20 Aug 2018 21:12:38 +0000 (14:12 -0700)
commitcafa0010cd51fb711fdcb50fc55f394c5f167a0a
tree59035cd5f8e7ea85abdd5ce278e820257f4a0663
parentcc26ebbebde8548014d9329ac2f6cf0178181789
Raise the minimum required gcc version to 4.6

Various architectures fail to build properly with older versions of the
gcc compiler.

An example from Guenter Roeck in thread [1]:
>
>   In file included from ./include/linux/mm.h:17:0,
>                    from ./include/linux/pid_namespace.h:7,
>                    from ./include/linux/ptrace.h:10,
>                    from arch/openrisc/kernel/asm-offsets.c:32:
>   ./include/linux/mm_types.h:497:16: error: flexible array member in otherwise empty struct
>
> This is just an example with gcc 4.5.1 for or32. I have seen the problem
> with gcc 4.4 (for unicore32) as well.

So update the minimum required version of gcc to 4.6.

[1] https://lore.kernel.org/lkml/20180814170904.GA12768@roeck-us.net/

Miscellanea:

 - Update Documentation/process/changes.rst

 - Remove and consolidate version test blocks in compiler-gcc.h for
   versions lower than 4.6

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/process/changes.rst
include/linux/compiler-gcc.h