Jon Smirl [off-list ref] writes:

Endianess comes into play when send/receiving multibyte integers on
platforms with different endianess.

It's the case when you're sending this data to a machine with
a different endianness. For example, in a network or to another CPU in
e.g. add-on card.
Ioctls are not affected by this, since both ends are the same.

Obviously you can be affected if you try to access data as integers in
one point and as arrays of bytes in the other, but it has nothing to do
with ioctls.
-- 
Krzysztof Halasa