Re: Copy_to_user/copy_from_user

[Ravi K <kravi26@yahoo.com>]

> > > As the kernel address space in the new linux
> > > kernels spans the entire 0 to 4 GB, still why 
> > > do we need to do copy_to_user or copy_from user
?

> > Because we can't be sure that the page is in
> > physical memory.

> If it's not, we'll just have to service a page
> fault; why's that a problem?

 I guess the main reason for using copy_to_user() and
copy_from_user() is the range-checking done there.
User-mode code should not be allowed to pass in a
kernel-mode address to kernel functions for read/write
operations.
 
-Regards,
 Ravi.

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