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LDD3的 scull和short模块调试:
scull的main.c中:
ssize_t scull_read(struct file *filp, char __user *buf, size_t count,
loff_t *f_pos)
{
struct scull_dev *dev = filp->private_data;
struct scull_qset *dptr; /* the first listitem */
int quantum = dev->quantum, qset = dev->qset;
int itemsize = quantum * qset; /* how many bytes in the listitem */
int item, s_pos, q_pos, rest;
ssize_t retval = 0;
printk(KERN_ALERT "scull:count= %ld\n",count);
...........................................
}
short的short.c中:
atomic li=ATOMIC_INIT(0);-------看发生了多少次中断
ssize_t do_short_read (struct inode *inode, struct file *filp, char __user *buf,
size_t count, loff_t *f_pos)
{
int retval = count, minor = iminor (inode);
unsigned long port = short_base + (minor&0x0f);
void *address = (void *) short_base + (minor&0x0f);
int mode = (minor&0x70) >> 4;
unsigned char *kbuf = kmalloc(count, GFP_KERNEL), *ptr;
printk(KERN_ALERT "short:count=%ld,li=%ld\n",count,atomic_read(&li));
if (!kbuf)
.........................................................
}
irqreturn_t short_interrupt(int,void*,struct pt_regs*)
{
atomic_inc(&li);
......
}
request_irq(irq,short_interrupt.....);
初始化时:安装了一个/proc/文件目录(通过create_proc_read_entry),名为short(主要是当cat /proc/short时能显示全局变量li的值
scull.ko对dd if=/dev/scull0 bs=2 count=1的printk反应是count=2,
short.ko对dd if=/dev/short0 bs=2(或bs=1) count=1的printk反应是count=0(2008年12月26日结果),有时count=4(2008年12月27日结果).
另外,我通过echo -ne "\377"> /dev/short0命令形式人为给/dev/short0发0xff(9脚和10脚相连,即引发中断),再dd if=/dev/short0 bs=1 count=1 ,do_short_read返回count=4,li=0,但是我马上cat /proc/short却显示li=2 (这就有两个问题1) 就是前面的问题为什么count=4: (2)do_short_read和/proc/short显示的li为什么不同,且我只发了一个中断li应该等于1
我继续echo -ne "\000" >/dev/short0 然后echo -ne "\377" >/dev/short0再次引发中断,同样do_short_read返回li=0,而/proc/short返回3
有时候不动电脑,过一会,cat /proc/interrupts 或cat /proc/short发现short_interrupt例程也执行了.
另外还发现一个现象:当上次unload模块之前echo -ne "\377" > /dev/short0
(即9和10脚高电平),然后再load模块,立即cat /proc/interrupts发现模块有中断,但cat /proc/short却又发现li=0
情帮忙分析分析,谢了! |
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发表于 2008-12-30 11:30
发表于 2008-12-31 20:52
