2009/9/17 Leonidas . <[email protected]>: > > > Hi list, > > I know that introducing/using new ioctls is frawned upon by the community. > They might still be needed for controlling various hw parameters, Just > wanted > to understand the data transfer side of ioctls with a use case. > > E.g. My kernel module needs to pass a buffer of 1-2Mb to userspace > whenever user requests. The buffer will contain different kind of data > depending > on different commands i.e. assume that I maintain 3 types of buffers in my > module. > > Now, with ioctls it is much easiler to get the buffer to userspace simply by > issusing > different commands. But if I have to achive the same functionality using > read() call > how would I do it? Meaning ioctl kind of multiplexes the things which might > be > needed in some cases. How would I do this kind of stuff with read()? By > having 3 > different minor devices and issuing read() on 3 devices for getting 3 > buffers? > hi, leo just implement your ioctl function, create the command, and decode command,deliver your command and buffer point (user) into your module,then use copy_from_user /copy_to_user deliver your buffer from user to kernel or vice versa.
> I am not looking for anyother mechanism of trasnfering data to userspace as > of now > since this data would be really sporadic. I have to choose between ioctl and > read. > > -Leo. > -- Best Regards Lin -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ
