won't a page fault be generated in case the page u r trying to copy to is not in the mem???????? On Mon, 2004-10-11 at 14:22, Pavan Kumar wrote: > copy_to_user/copy_from_user takes care of address not in memory (page > fault), For x86 atleast u can do blind memcpy ( it not > recommended/portable though ). > Pl. correct me if i am wrong. > > On Mon, 11 Oct 2004 09:41:30 +0200, Jan Hudec <bulb@xxxxxx> wrote: > > On Mon, Oct 11, 2004 at 09:55:37 +0530, mohanlal jangir wrote: > > > I have a character device and some of its functions are being called by > > > ioctl. In a function, I do copy_to_user and copy_from_user to get the user > > > space data in kernel memory. My question is, if this function doesn't sleep, > > > can I avoid calls to copy_to_user and copy_from_user? > > > > No, you can't. The user-space memory is not directly addressable from > > kernel. > > > > ------------------------------------------------------------------------------- > > Jan 'Bulb' Hudec <bulb@xxxxxx> > > > > > > > > -- > Kernelnewbies: Help each other learn about the Linux kernel. > Archive: http://mail.nl.linux.org/kernelnewbies/ > FAQ: http://kernelnewbies.org/faq/ > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
