error: implicit declaration of function 'acquire_console_sem'错误解决方法

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我是靠谱客的博主昏睡鸵鸟，最近开发中收集的这篇文章主要介绍error: implicit declaration of function 'acquire_console_sem'错误解决方法，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

ubuntu12.10下编译Android4.0内核源代码

1.问题：

kernel/power/consoleearlysuspend.c:28:2: error: implicit declaration of function 'acquire_console_sem'

2.解决方法：

修改源代码根目录下kernel/power/consoleearlysuspend.c文件，将acquire_console_sem()与release_console_sem()函数分别换为console_lock()与console_unlock()函数

3.分析：

函数acquire_console_sem()与release_console_sem()用来获得和释放互斥锁console_sem；新内核下这两个函数变成console_lock()与console_unlock()，故替换之便OK.

4.附：console_lock()与console_unlock()函数位置：内核源代码根目录下kernel/printk.c文件1222行

/**
* console_lock - lock the console system for exclusive use.
*
* Acquires a lock which guarantees that the caller has
* exclusive access to the console system and the console_drivers list.
*
* Can sleep, returns nothing.
*/
void console_lock(void)
{
        BUG_ON(in_interrupt());
        down(&console_sem);
        if (console_suspended)
                return;
        console_locked = 1;
        console_may_schedule = 1;
}
EXPORT_SYMBOL(console_lock);

/**
* console_unlock - unlock the console system
*
* Releases the console_lock which the caller holds on the console system
* and the console driver list.
*
* While the console_lock was held, console output may have been buffered
* by printk(). If this is the case, console_unlock(); emits
* the output prior to releasing the lock.
*
* If there is output waiting for klogd, we wake it up.
*
* console_unlock(); may be called from any context.
*/
void console_unlock(void)
{
        unsigned long flags;
        unsigned _con_start, _log_end;
        unsigned wake_klogd = 0;

        if (console_suspended) {
                up(&console_sem);
                return;
        }

        console_may_schedule = 0;

        for ( ; ; ) {
                spin_lock_irqsave(&logbuf_lock, flags);
                wake_klogd |= log_start - log_end;
                if (con_start == log_end)
                        break;                  /* Nothing to print */
                _con_start = con_start;
                _log_end = log_end;
                con_start = log_end;            /* Flush */
                spin_unlock(&logbuf_lock);
                stop_critical_timings();        /* don't trace print latency */
                call_console_drivers(_con_start, _log_end);
                start_critical_timings();
                local_irq_restore(flags);
        }
        console_locked = 0;

        /* Release the exclusive_console once it is used */
        if (unlikely(exclusive_console))
                exclusive_console = NULL;

        up(&console_sem);
        spin_unlock_irqrestore(&logbuf_lock, flags);
        if (wake_klogd)
                wake_up_klogd();
}
EXPORT_SYMBOL(console_unlock);