基于cygwin构建u-boot（二）gcc的C语言标准版本号（-std=）

接上文，修改Makefile和config.mk中，.depend相关文件格式后继续编译。

四、tools文件夹的文件编译错误

错误告警如下【多行信息，请使用右侧滚动条查看】：

 gcc -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -idirafter /u-boot-2010.09/u-boot-2010.09/include 
    -idirafter /u-boot-2010.09/u-boot-2010.09/include2 -idirafter /u-boot-2010.09/u-boot-2010.09/include 
    -I /u-boot-2010.09/u-boot-2010.09/lib/libfdt -I /u-boot-2010.09/u-boot-2010.09/tools 
    -DTEXT_BASE=0x11080000 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -ansi   -o default_image.o default_image.c -c
 In file included from fdt_host.h::,
                  from mkimage.h:,
                  from default_image.c::
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘struct’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 ../include/libfdt.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 In file included from default_image.c:::
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint8_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint8_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint8_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint8_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘char’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘ulong’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘uint32_t’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘ulong’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘int’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘ulong’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘ulong’
 /u-boot-2010.09/u-boot-2010.09/include/image.h::: 错误：expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘const’
 default_image.c: 在函数‘image_set_header’中:
 default_image.c::: 警告：隐式声明函数‘image_set_magic’
 default_image.c::: 警告：隐式声明函数‘image_set_time’
 default_image.c::: 警告：隐式声明函数‘image_set_size’
 default_image.c::: 警告：隐式声明函数‘image_set_load’
 default_image.c::: 警告：隐式声明函数‘image_set_ep’
 default_image.c::: 警告：隐式声明函数‘image_set_dcrc’
 default_image.c::: 警告：隐式声明函数‘image_set_os’
 default_image.c::: 警告：隐式声明函数‘image_set_arch’
 default_image.c::: 警告：隐式声明函数‘image_set_type’
 default_image.c::: 警告：隐式声明函数‘image_set_comp’
 default_image.c::: 警告：隐式声明函数‘image_set_name’
 default_image.c::: 警告：隐式声明函数‘image_set_hcrc’
 /u-boot-2010.09/u-boot-2010.09/rules.mk:: recipe for target `default_image.o' failed
 make[]: *** [default_image.o] Error
 make[]: 离开目录“/u-boot-2010.09/u-boot-2010.09/tools”
 Makefile:: recipe for target `tools' failed
 make: *** [tools] Error 

1、首先，需要了解gcc的错误告警信息。

1）错误位置：文件名：行号：列号。【注意：gcc工具的告警信息不是很友好，显示的错误位置可能不是真实的位置】

2）引用关系：错误提示中，第2～4行，表示头文件的引用关系（一层一层的引用）。

default_image.c 第30行 -- mkimage.h 第35行 -- fdt_host.h第25行-- libfdt.h

3）主要的错误类型： 错误：expected '=', ',', ';', 'asm' or '__attribute__' before

初步搜索，发现该问题和 头文件中 inline 关键字相关。

 GCC implements three different semantics of declaring a function inline. One is available with ‘-std=gnu89’ or ‘-fgnu89-inline’ or when gnu_inline attribute is present on all inline declarations, another when ‘-std=c99’ or ‘-std=gnu99’ (without ‘-fgnu89-inline’), and the third is used when compiling C++.
 To declare a function inline, use the inline keyword in its declaration, like this:
     static inline int inc (int *a)
     {
         (*a)++;
     }
 If you are writing a header file to be included in ISO C89 programs, write __inline__ instead of inline

2、从错误信息可以看到，gcc包含了参数 -ansi。

而 -ansi，对于gcc工具就等于 -std=c89。

在libfdt.h文件中，第162行如下

static inline void *fdt_offset_ptr_w(void *fdt, int offset, int checklen)

告警信息为第15列，void是错误的信息，gcc认为缺少 ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’

3、找到-ansi的位置并修改。

U-boot 编译工具相关的配置，都在主文件夹 config.mk文件中，

 ifeq ($(HOSTOS),cygwin)
 HOSTCFLAGS    += -ansi
 endif

从配置中可以，u-boot认为在cygwin下，需要增加-ansi的编译选型。

但实际，由于u-boot-2010.09文件是根据C99规范编写的，应该删除该信息。

4、gcc工具编译错误的问题得到解决。

 gcc -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer  -idirafter /u-boot-2010.09/u-boot-2010.09/include  
    -idirafter /u-boot-2010.09/u-boot-2010.09/include2  -idirafter /u-boot-2010.09/u-boot-2010.09/include  
    -I /u-boot-2010.09/u-boot-2010.09/lib/libfdt  -I /u-boot-2010.09/u-boot-2010.09/tools  
    -DTEXT_BASE=0x11080000 -DUSE_HOSTCC  -D__KERNEL_STRICT_NAMES -pedantic   -o img2srec.o img2srec.c -c
 gcc -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer  -idirafter /u-boot-2010.09/u-boot-2010.09/include  
    -idirafter /u-boot-2010.09/u-boot-2010.09/include2  -idirafter /u-boot-2010.09/u-boot-2010.09/include  
    -I /u-boot-2010.09/u-boot-2010.09/lib/libfdt  -I /u-boot-2010.09/u-boot-2010.09/tools  
    -DTEXT_BASE=0x11080000 -DUSE_HOSTCC  -D__KERNEL_STRICT_NAMES -pedantic  -o img2srec img2srec.o
 strip img2srec

可以看到正常生成了 img2srec.o

5、后记

C语言标准比较多，gcc支持的也比较多，相关关键字有：

gcc-4.5支持的C语言标准
 1 -ansi In C mode, this is equivalent to ‘-std=c89’. In C++ mode, it is equivalent to ‘-std=c++’.
 -std= Determine the language standard. A value for this option must be provided; possible values are
     ‘c89’
     ‘iso9899:’
             Support all ISO C90 programs (certain GNU extensions that conflict
             with ISO C90 are disabled). Same as ‘-ansi’ for C code.
     ‘iso9899:’
             ISO C90 as modified in amendment .
     ‘c99’
     ‘c9x’
11     ‘iso9899:’
12     ‘iso9899:199x’
             ISO C99. Note that this standard is not yet fully supported;
             see http://gcc.gnu.org/gcc-4.3/c99status.html for more information.
             The names ‘c9x’ and ‘iso9899:199x’ are deprecated.
     ‘gnu89’ GNU dialect of ISO C90 (including some C99 features). This is the default for C code.
17     ‘gnu99’
     ‘gnu9x’ GNU dialect of ISO C99. When ISO C99 is fully implemented in GCC, this will become the default. 
               The name ‘gnu9x’ is deprecated.
     ‘c++’ The  ISO C++ standard plus amendments. Same as ‘-ansi’ for C++ code.
     ‘gnu++’ GNU dialect of ‘-std=c++’. This is the default for C++ code.
     ‘c++0x’ The working draft of the upcoming ISO C++0x standard. This option enables experimental features 
               that are likely to be included in C++0x. The working draft is constantly changing, 
               and any feature that is enabled by this flag may be removed from future versions of GCC 
               if it is not part of the C++0x standard.
     ‘gnu++0x’ GNU dialect of ‘-std=c++0x’. This option enables experimental features 
               that may be removed in future versions of GCC.

===【未完待续】===