On Sat, Mar 08, 2025 at 03:07:25PM +0100, Peter Skvarka wrote: > Hello, > > I call ioctl() containing request code created with _IOR(..., mystruct) > and kernel module processed it. > When I create instance of mystruct, fill it's members with some values and I > pass it's pointer like third parameter to ioctl() then members of structure > appears zeroed in kernel code. > > Is it correct behavior or am I doing something wrong ?
Yes, _IOR only reads data from the kernel (copies the result structure out to userland), nothing is copied in from userland to kernel. _IOW only copies in (userland -> kernel), _IORW does both. Martin
