On Wed, 22 Mar 2023 11:27:25 +0000 Donald Hunter wrote:

quoted

So in terms of C this treats the payload of the attr as a packed array?
That's not what array-nest is, array-nest wraps every entry in another
nlattr:
https://docs.kernel.org/next/userspace-api/netlink/genetlink-legacy.html#array-nest

It's not a C array dumped into an attribute.

IIRC I was intending to use 'binary' for packed arrays. Still use
sub-type to carry the type, but main type should be 'binary'.

If that sounds reasonable could you document or remind me to document
this as the expected behavior? Sub-type appears completely undocumented
now :S  

That sounds reasonable, yes. I will also rename the method to
'as_c_array'. I think it should just be restricted to scalar subtypes,
i.e. u16, u32, etc. Do you agree?

We can limit it to scalars for now. There are some arrays of structs
(from memory TC GRED had VCs defined as array of structs?) but that
should hopefully be rare and can be added later.