interview question how does application connects to device

[Javier Martinez Canillas]

>> My question is, why netlink sockets are better than ioctls? It is not
>> yet another interface to use as a wildcard to pass any data you wan't
>> between the kernel and userpace with the only difference that you use
>> another paradigm? (network sockets with a specific protocol family
>> instead file operations over a device).
>>
>> Sorry if my question is stupid but I just don't get the point.
>>
>> Regards,
>>
> Javier,
>
> I think the main issue with ioctl is that with some architectures, the
> userspace and kernel compiler treat 64-bit structure members
> differently, so it is very easy to create a structure which can not
> easily be passed via a simple pointer in-all-architectures.
>
> With netlink sockets, one is expected to have a well defined byte
> order coming across the socket.
>
> Greg
>

Greg,

Thank you very much for your answer, I wasn't aware of that ioctl limitation.

Best regards,

-- 
Javier Martínez Canillas
(+34) 682 39 81 69
PhD Student in High Performance Computing
Computer Architecture and Operating System Department (CAOS)
Universitat Autònoma de Barcelona
Barcelona, Spain