> > > 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. __________________________________________________ Do You Yahoo!? Send your FREE holiday greetings online! http://greetings.yahoo.com -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ IRC Channel: irc.openprojects.net / #kernelnewbies Web Page: http://www.kernelnewbies.org/
