项目场景：
linux内核编译错误
问题描述：
CC [M] /home/wyong/imx6ull/1_chrdevbase/chrdevbase.o
In file included from ./arch/x86/include/asm/bitops.h:16:0,
from include/linux/bitops.h:36,
from include/linux/kernel.h:10,
from /home/wyong/imx6ull/1_chrdevbase/chrdevbase.c:2:
./arch/x86/include/asm/arch_hweight.h: In function ‘__arch_hweight64’:
./arch/x86/include/asm/arch_hweight.h:53:42: error: expected ‘:’ or ‘)’ before ‘POPCNT64’
asm (ALTERNATIVE("call __sw_hweight64", POPCNT64, X86_FEATURE_POPCNT)
^
./arch/x86/include/asm/alternative.h:125:28: note: in definition of macro ‘ALTINSTR_REPLACEMENT’
b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n\t"
^
./arch/x86/include/asm/arch_hweight.h:53:7: note: in expansion of macro ‘ALTERNATIVE’
asm (ALTERNATIVE("call __sw_hweight64", POPCNT64, X86_FEATURE_POPCNT)
^
In file included from ./arch/x86/include/asm/pgtable_types.h:250:0,
from ./arch/x86/include/asm/processor.h:18,
from ./arch/x86/include/asm/thread_info.h:49,
from include/linux/thread_info.h:54,
from ./arch/x86/include/asm/preempt.h:6,
from include/linux/preempt.h:18,
from include/linux/spinlock.h:50,
from include/linux/seqlock.h:35,
from include/linux/time.h:5,
from include/uapi/linux/timex.h:56,
from include/linux/timex.h:56,
from include/linux/sched.h:19,
from include/linux/blkdev.h:4,
from include/linux/ide.h:12,
from /home/wyong/imx6ull/1_chrdevbase/chrdevbase.c:4:
include/asm-generic/pgtable-nopud.h: At top level:
include/asm-generic/pgtable-nopud.h:15:0: warning: "PUD_SHIFT" redefined
#define PUD_SHIFT PGDIR_SHIFT
^
In file included from ./arch/x86/include/asm/pgtable_types.h:205:0,
from ./arch/x86/include/asm/processor.h:18,
from ./arch/x86/include/asm/thread_info.h:49,
from include/linux/thread_info.h:54,
from ./arch/x86/include/asm/preempt.h:6,
from include/linux/preempt.h:18,
from include/linux/spinlock.h:50,
from include/linux/seqlock.h:35,
from include/linux/time.h:5,
from include/uapi/linux/timex.h:56,
from include/linux/timex.h:56,
./arch/x86/include/asm/cache.h:7:25: error: ‘CONFIG_X86_L1_CACHE_SHIFT’ undeclared here (not in a function)
#define L1_CACHE_SHIFT (CONFIG_X86_L1_CACHE_SHIFT)
^
./arch/x86/include/asm/cache.h:8:30: note: in expansion of macro ‘L1_CACHE_SHIFT’
#define L1_CACHE_BYTES (1 << L1_CACHE_SHIFT)
^
include/linux/cache.h:12:25: note: in expansion of macro ‘L1_CACHE_BYTES’
#define SMP_CACHE_BYTES L1_CACHE_BYTES
^
include/linux/cache.h:20:58: note: in expansion of macro ‘SMP_CACHE_BYTES’
#define ____cacheline_aligned __attribute__((__aligned__(SMP_CACHE_BYTES)))
^
./arch/x86/include/asm/processor.h:270:27: note: in expansion of macro ‘____cacheline_aligned’
} __attribute__((packed)) ____cacheline_aligned;
./arch/x86/include/asm/processor.h: In function ‘current_top_of_stack’:
./arch/x86/include/asm/processor.h:594:30: error: ‘cpu_current_top_of_stack’ undeclared (first use in this function)
return this_cpu_read_stable(cpu_current_top_of_stack);
^
./arch/x86/include/asm/percpu.h:213:9: note: in definition of macro ‘percpu_stable_op’
typeof(var) pfo_ret__; \
^
./arch/x86/include/asm/processor.h:594:9: note: in expansion of macro ‘this_cpu_read_stable’
return this_cpu_read_stable(cpu_current_top_of_stack);
^
./arch/x86/include/asm/processor.h:594:30: note: each undeclared identifier is reported only once for each function it appears in
return this_cpu_read_stable(cpu_current_top_of_stack);
^
./arch/x86/include/asm/percpu.h:213:9: note: in definition of macro ‘percpu_stable_op’
typeof(var) pfo_ret__; \
^
./arch/x86/include/asm/atomic64_64.h:207:45: error: unknown type name ‘atomic64_t’
static inline long atomic64_dec_if_positive(atomic64_t *v)
^
In file included from include/linux/sched.h:32:0,
from include/linux/blkdev.h:4,
from include/linux/ide.h:12,
from /home/wyong/imx6ull/1_chrdevbase/chrdevbase.c:4:
include/linux/cputime.h:4:25: fatal error: asm/cputime.h: No such file or directory
compilation terminated.
scripts/Makefile.build:264: recipe for target '/home/wyong/imx6ull/1_chrdevbase/chrdevbase.o' failed
make[2]: *** [/home/wyong/imx6ull/1_chrdevbase/chrdevbase.o] Error 1
Makefile:1384: recipe for target '_module_/home/wyong/imx6ull/1_chrdevbase' failed
make[1]: *** [_module_/home/wyong/imx6ull/1_chrdevbase] Error 2
原因分析与解决方法：
怀疑是编译器的问题，在执行make时没有找到指定的编译器，做了实现验证编译器能不能使用，验证是可以的。在命令行中增加
ARCH=arm
CROSS_COMPILE=arm-linux-gnueabi-
然后在执行make仍然有错误
1）在命令行下执行，这样是可以编译的
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-
2）在Makefile中添加变量，在编译（CC）阶段，使用这个变量
MAKE_ENV := ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-
...
$(CC) $(MAKE_ENV)