Re: [RFA] namespaces and vendor extensions

On Tue, Dec 1, 2009 at 1:16 AM, Johannes Berg <[email protected]> wrote:
> Joshua,
>
>> For the structure of the vendor space, you extend 'skip_length' from 8
>> bits to 16 bits.
>> > Structure
>> >        u8 OUI[3], u8 sub_namespace, __le16 skip_length
>> I'm neutral on that. My question is why not extend 'sub_namespace' to
>> 16 bits too?
>
> I don't see much point in having more than 255 sub-namespaces per OUI,
> do you?
>
>> I hardly see that a vendor extension part can go over 255
>> bytes. But if that happens, it's quite likely that the extension may
>> contain more than 8 fields.
>
> Where are you taking 8 fields from? After the vendor extensions bit, the
> vendor extension puts vendor-defined presence bits into the it_present
> bitmap. Therefore, you have an unlimited number of fields per vendor
> sub-namespace, as such I see little reason to support more than 255
> sub-namespaces.

Wanted to clarify, on the vendor it_present bitmap, does it always
have to also respect the bit for vendor extension bit 30? The current
proposal seems to have language which would indicates so:

"This field is reserved in all namespaces and every it_present word,
the standard radiotap namespace as well as all vendor namespaces. "

If so what is the point of the reset bit? What I mean is that if we
give radiotap its own OUI technically we could just reset ourselves to
the radiotap namespace by specifying the radiotap OUI with what I'd
think would be optional radiotap subnamespace material (length could
be 0 I take it).

  Luis