如何判断编译时glibc中某个宏在哪里定义的？

harry_he

我在编译native u-boot的时候，碰到vdprintf没有定义的问题，后来发现是因为宏__USE_XOPEN2K8没有打开的原因，但是这个宏只在glibc中使用了，u-boot并没有使用它，而且应不应该去使用它。如果使用交叉编译器没有这样的问题，__USE_XOPEN2K8似乎被定义了。那么我如何检查这个宏到底是在哪里定义的呢？gcc会传递一些缺省宏吧？glibc也有一些宏是打开的。有没有办法可以列出编译过程中哪些宏被打开了？

qtdszws

1. 
   
2. [root@mail ~/gcc-3.0/build/gcc]# cat 1.c
   
3. #define A 1
   
4. #undef A
   
5. 
   
6. [root@mail ~/gcc-3.0/build/gcc]# gcc -E -dD 1.c
   
7. # 1 "1.c"
   
8. # 1 "<built-in>"
   
9. #define __VERSION__ "3.2.2 20030222 (Red Hat Linux 3.2.2-5)"
   
10. #define __USER_LABEL_PREFIX__
    
11. #define __REGISTER_PREFIX__
    
12. #define __HAVE_BUILTIN_SETJMP__ 1
    
13. #define __SIZE_TYPE__ unsigned int
    
14. #define __PTRDIFF_TYPE__ int
    
15. #define __WCHAR_TYPE__ long int
    
16. #define __WINT_TYPE__ unsigned int
    
17. #define __STDC__ 1
    
18. # 1 "<command line>"
    
19. #define __GNUC__ 3
    
20. # 1 "<command line>"
    
21. #define __GNUC_MINOR__ 2
    
22. # 1 "<command line>"
    
23. #define __GNUC_PATCHLEVEL__ 2
    
24. # 1 "<command line>"
    
25. #define __GXX_ABI_VERSION 102
    
26. # 1 "<command line>"
    
27. #define __ELF__ 1
    
28. # 1 "<command line>"
    
29. #define unix 1
    
30. # 1 "<command line>"
    
31. #define __gnu_linux__ 1
    
32. # 1 "<command line>"
    
33. #define linux 1
    
34. # 1 "<command line>"
    
35. #define __ELF__ 1
    
36. # 1 "<command line>"
    
37. #define __unix__ 1
    
38. # 1 "<command line>"
    
39. #define __gnu_linux__ 1
    
40. # 1 "<command line>"
    
41. #define __linux__ 1
    
42. # 1 "<command line>"
    
43. #define __unix 1
    
44. # 1 "<command line>"
    
45. #define __linux 1
    
46. # 1 "<command line>"
    
47. #define __NO_INLINE__ 1
    
48. # 1 "<command line>"
    
49. #define __STDC_HOSTED__ 1
    
50. # 1 "<command line>"
    
51. #define i386 1
    
52. # 1 "<command line>"
    
53. #define __i386 1
    
54. # 1 "<command line>"
    
55. #define __i386__ 1
    
56. # 1 "<command line>"
    
57. #define __tune_i386__ 1
    
58. # 1 "1.c"
    
59. #define A 1
    
60. #undef A
    
61. [root@mail ~/gcc-3.0/build/gcc]# gcc -E -dM 1.c
    
62. #define __HAVE_BUILTIN_SETJMP__ 1
    
63. #define __unix__ 1
    
64. #define unix 1
    
65. #define __i386__ 1
    
66. #define __SIZE_TYPE__ unsigned int
    
67. #define __ELF__ 1
    
68. #define __GNUC_PATCHLEVEL__ 2
    
69. #define __linux 1
    
70. #define __unix 1
    
71. #define __linux__ 1
    
72. #define __USER_LABEL_PREFIX__
    
73. #define linux 1
    
74. #define __STDC_HOSTED__ 1
    
75. #define __WCHAR_TYPE__ long int
    
76. #define __gnu_linux__ 1
    
77. #define __WINT_TYPE__ unsigned int
    
78. #define __GNUC__ 3
    
79. #define __GXX_ABI_VERSION 102
    
80. #define i386 1
    
81. #define __GNUC_MINOR__ 2
    
82. #define __STDC__ 1
    
83. #define __PTRDIFF_TYPE__ int
    
84. #define __tune_i386__ 1
    
85. #define __REGISTER_PREFIX__
    
86. #define __NO_INLINE__ 1
    
87. #define __i386 1
    
88. #define __VERSION__ "3.2.2 20030222 (Red Hat Linux 3.2.2-5)"
    

复制代码

harry_he

谢谢，真得很有用