Re: Why system call need to copy the date from the userspace before using it

Tomko
2005-04-14T02:10:43Z

Catalin Marinas wrote:

>Tomko <tomko@haha.com> wrote:
>
>
>>Inside the system call , the kernel often copy the data by calling
>>copy_from_user() rather than just using strcpy(), is it because the
>>memory mapping in kenel space is different from user space?
>>
>>
>
>No, it is because this function checks whether the access to the user
>space address is OK. There are situations when it can also sleep (page
>not present).
>
>
>
what u means "OK"? kernel space should have right to access any memory
address , can u expained in details what u means "OK"?