为什么u-boot2016-11移植会出现报错？

./arch/ARM/include/asm/unified.h: Assembler messages:
./arch/arm/include/asm/unified.h:13: Error: unknown pseudo-op: `.syntax'
scripts/Makefile.build:316: recipe for target 'arch/arm/lib/ashldi3.o' failed
make[1]: *** [arch/arm/lib/ashldi3.o] Error 1
Makefile:1233: recipe for target 'arch/arm/lib' failed

/arch/arm/include/asm/unified.h 报错的地方在下面红色字
#if defined(__ASSEMBLY__) && defined(CONFIG_ARM_ASM_UNIFIED)
        .syntax unified
#endif
这个我查了是统一arm 指令集的作用，但gcc报错感觉是不认识这个玩意。可是为什么不认识呢？？
注释掉这句后
arch/arm/lib/div64.S: Assembler messages:
arch/arm/lib/div64.S:92: Error: bad instruction `subscs r1,r1,r2'
arch/arm/lib/div64.S:93: Error: bad instruction `movsne ip,ip,lsr#1'
scripts/Makefile.build:316: recipe for target 'arch/arm/lib/div64.o' failed
后面的一些指令也不认识了。