kbuild: add KBUILD_DEFCONFIG ...

This allows "make ARCH=... defconfig".

Fox example, you can type "make defconfig" instead of
"make sandbox_defconfig".

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/x86: fix link with recent gcc ...

Due to unwind tables being generated by recent versions of gcc by
default, the x86 Barebox link fails with:

ld: section .eh_frame loaded at [00000000000197c4,000000000001f31f]
overlaps section .barebox_initcalls loaded at [00000000000197c4,0000000000019833]

Passing -fno-unwind-tables -fno-asynchronous-unwind-tables avoids this
problem.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Makefile: generate a barebox-flash-image link ...

Depending on the SoC a barebox.bin, barebox.netx, barebox.s5p, MLO image
is generated. With pbl support there now is an additional
arch/arm/pbl/zbarebox.bin image.

To help the user to determine which image should be flashed to his device,
generate a barebox-flash-image link.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

Only pass -P to cpp when generating ld scripts ...

When building sandbox with ccache, one would hit warnings such as:
    warning: 'struct mmsghdr' declared inside parameter list
on random files; a way to reproduce this issue is to build a simple
file doing just:
    #include <sys/socket.h>

    int main(void) {
        return 0;
    }

    gcc -Wall -P -c -o foo foo.c

But actually the -P flag is only useful when generating non-C files,
such as linker scripts in the case of barebox.  Removing the -P flag
from all the gcc invocations, except when generating .lds files makes
the warning go away.  It turns out that this is what
linux/scripts/Makefile.build also does nowadays.

Signed-off-by: Loïc Minier <loic.minier@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

x86: Use the generic linker script initializing ...

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>

x86: Remove not used expressions from the makefile ...

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>

x86: add 64bit host build support ...

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

move boards to arch/<architecure>/boards ...

this will allow each arch to handle the boards more simply and depending on
there need

the env var BOARD will refer to the current board dirent

for sandbox as we have only one board the board dirent is arch/sandbox/board

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add the whole x86 architecture to the build system ...

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>