Dear sir, I know that there are two ways to access kernel of Linux. One way is to use funstions of open and ioctl. The following is part of the driver for pcmcia /*This part is in kernel space and register a driver named "pcmcia"*/ ...... static struct file_operations ds_fops={ .owner=THIS_MODULE; .open=ds_open, .release=ds_release, ioctl=ds_ioctl, read=ds_read, write=ds_write, poll=ds_poll, } ...... register_chrdev(0, "pcmcia", &ds_fops) /*This part is in user space and access pcmcia*/ fd=open("/dev/pcmcia",...）;/*open the device*/ ioctl(fd,...,...);/*control the device*/ question 1: Can I register my driver in the kernel and then access the kernel in Mac OS X like that? And another way is to use system call. In linux ,I can write a kernel extension called my_kerneltest like this: int my_kerneltest(const char *path) { return 0; } int init_module(void) { sys_call_table[SYS_kerneltest]=my_kerneltest; return 0; } void cleanup_module(void) { ...... } And in user space ,I can use my kernel with function of my_kerneltest() question2:Can I create my system call in the kernel and use it in user space in Mac OS X like that? Thank you! Yours Sincerely Ye Wenxi in Tokyo _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.