[U-Boot] [PATCH] arm: rmobile: Support build with gcc-4.6 or later

[Tetsuyuki Kobayashi <koba@kmckk.co.jp>]

Hello, Iwamatsu-san

(2012/07/06 9:06), Nobuhiro Iwamatsu wrote:
> Latest rmobile code was tested by using old gcc (gcc-4.4).
> When we use gcc-4.6 (or later), the build is made, but does not work.
> This solves a problem not to work by add -march=armv5 to compiple option
> when we built in gcc-4.6 (or later).
> I tested by linaro's compiler version 2012.04-20120426.

Yes. I know recent gcc causes problem because of unaligned access.
There are 2 different proposals, but neither accepted.

[PATCH] arm: enable unaligned access on ARMv7
http://lists.denx.de/pipermail/u-boot/2012-June/125754.html

[PATCH] arm: armv7: add compile option -mno-unaligned-access if available
http://lists.denx.de/pipermail/u-boot/2012-July/127260.html

This patch is the third one.

> --- a/arch/arm/cpu/armv7/rmobile/lowlevel_init.S
> +++ b/arch/arm/cpu/armv7/rmobile/lowlevel_init.S
> @@ -49,8 +49,6 @@ wait_interrupt:
>   	str     r2, [r1]
>   
>   wait_loop:
> -	wfi
> -
>   	ldr		r2, [r1, #0xC]
>   	str		r2, [r1, #0x10]

I know "wfi" instruction causes compile error in -march=armv5.
Without this, it works but not so good because 2nd CPU wastes cycles.

I wonder, is there any cheat such as ".word 0x...." (putting instruction code directly)
or something.