MACHINE_START MACHINE_END 宏(三)
#define __define_initcall(level,fn,id) \
static initcall_t __initcall_##fn##id __used \
__attribute__((__section__(".initcall" level ".init"))) = fn
展开就是static initcall_t __initcall_customize_machine3 __used __attribute__((__section__(".initcall3.init")))=customize_machine
在vmlinux.lds中
[cpp]
__initcall_start = .;
*(.initcallearly.init)
__early_initcall_end = .;
*(.initcall0.init)
*(.initcall0s.init)
*(.initcall1.init)
*(.initcall1s.init)
*(.initcall2.init)
*(.initcall2s.init)
*(.initcall3.init)
*(.initcall3s.init)
*(.initcall4.init)
*(.initcall4s.init)
*(.initcall5.init)
*(.initcall5s.init)
*(.initcallrootfs.init)
*(.initcall6.init)
*(.initcall6s.init)
*(.initcall7.init)
*(.initcall7s.init)
__initcall_end = .;
标注为.initcall3.init的函数编译进__initcall_start和__initcall_end框起的section中
而在
系统启动的时候
start_kernel->rest_init()->kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);创建了kernel线程
kernel_init->do_pre_smp
static void __init do_pre_smp_initcalls(void)
{
initcall_t *fn;
for (fn = __initcall_start; fn < __early_initcall_end; fn++)
do_one_initcall(*fn);
}
该函数遍历__initcall_start和__early_initcall_end中的函数,并调用do_one_initcall
[cpp]
int __init_or_module do_one_initcall(initcall_t fn)
{
int count = preempt_count();
int ret;
if (initcall_debug)
ret = do_one_initcall_debug(fn);
else
ret = fn();//执行了fn函数也就是customize_machine
msgbuf[0] = 0;
if (ret && ret != -ENODEV && initcall_debug)
sprintf(msgbuf, "error code %d ", ret);
if (preempt_count() != count) {
strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
preempt_count() = count;
}
if (irqs_disabled()) {
strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
local_irq_enable();
}
if (msgbuf[0]) {
printk("initcall %pF returned with %s\n", fn, msgbuf);
}
return ret;
}