Linux IOCTL commands -


trying implement ioctl commands, , encountered below:

if _io both read , write

than why should consider _ior , _iow

any clue please ?

actually _io ioctls don't take parameters @ all. instance, want trigger command has been set in driver, may not need pass data @ all!

_iowr ioctls pass parameters in , out. in experience these rare , can confusing since 1 parameter utilized 2 different purposes can useful when need it.

see beginning of http://www.mjmwired.net/kernel/documentation/ioctl-number.txt

there isn't in kernel enforces direction, documentation purposes.


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