include/linux/init.h中有
#define __init __section(.init.text) __cold notrace
#define __initdata __section(.init.data)
#define __initconst __constsection(.init.rodata)
#define __exitdata __section(.exit.data)
#define __exit_call __used __section(.exitcall.exit)
其中__section(xxx)为宏定义，展开后
# define __section(S) __attribute__ ((__section__(#S)))
section ("SECTION-NAME")'
Normally, the compiler places the objects it generates in sections
like `data' and `bss'. Sometimes, however, you need additional
sections, or you need certain particular variables to appear in
special sections, for example to map to special hardware. The
`section' attribute specifies that a variable (or function) lives
in a particular section. For example, this small program uses
several specific section names:
struct duart a __attribute__ ((section ("DUART_A"))) = { 0 };
struct duart b __attribute__ ((section ("DUART_B"))) = { 0 };
char stack[10000] __attribute__ ((section ("STACK"))) = { 0 };
int init_data __attribute__ ((section ("INITDATA"))) = 0;
main()
{
/* Initialize stack pointer */
init_sp (stack + sizeof (stack));
/* Initialize initialized data */
memcpy (&init_data, &data, &edata - &data);
/* Turn on the serial ports */
init_duart (&a);
init_duart (&b);
}
Use the `section' attribute with an _initialized_ definition of a
_global_ variable, as shown in the example. GCC issues a warning
and otherwise ignores the `section' attribute in uninitialized
variable declarations.
You may only use the `section' attribute with a fully initialized
global definition because of the way linkers work. The linker
requires each object be defined once, with the exception that
uninitialized variables tentatively go in the `common' (or `bss')
section and can be multiply "defined". You can force a variable
to be initialized with the `-fno-common' flag or the `nocommon'
attribute.
Some file formats do not support arbitrary sections so the
`section' attribute is not available on all platforms. If you
need to map the entire contents of a module to a particular
section, consider using the facilities of the linker instead.
可以看出为将对应的函数，变量等放到指定的段中