From my perspective it is useful to have the driver express whether

or not it supports this parameter.  It may not change how the system
operates, but it will be useful in testing to determine whether it
is expected that a (given version of a) driver is expected to act
with respect to this property so we can flag issues with the
implementation.

On Wed, Dec 2, 2015 at 8:38 AM, Dan Williams [off-list ref] wrote:

On Wed, 2015-12-02 at 14:32 +0100, Arend van Spriel wrote:

quoted

On 12/01/2015 12:08 PM, Jouni Malinen wrote:

quoted

On Tue, Dec 01, 2015 at 11:48:32AM +0200, Kalle Valo wrote:

quoted

Arend van Spriel [off-list ref] writes:

quoted

It solves a problem for us, but admittedly it is not something
that is
very usable by user-space apps. So I guess what you are
suggesting
here is to come up with a nl80211 api for this. On the mailing
list
(or hostap list) the topic pops up from time to time so there
are
people who would like to have such a knob to play with. Still
would
like to keep the module parameter although its use may change
when
nl80211 api is added.

I don't know what is the best approach, that's why I would like
to hear
opinions from others. Personally I don't like the idea of adding
802.11
level configuration options to module parameters, but on the
other hand
I don't have any strong opinions about this.

I would like to see this as a new attribute to NL80211_CMD_CONNECT
to
provide parameters for offloaded (driver and/or firmware) BSS
selection
and roaming. If there is a driver that uses roaming offload with
NL80211_CMD_ASSOCIATE, the same attribute could be used there (but
I'm
not sure how exact such offloading would work in practice since I'd
expect both authentication and (re)association to be offloaded).

Sounds reasonable. Just would like to explore the use-case a bit
more.
Looking at tools like NetworkManager and android network list, the
user
is always presented with just SSID listed once. For NetworkManager

While NM has band locking properties, there is currently no "prefer
5ghz" since as Jouni said, the supplicant should probably just prefer
5ghz right now.  In any case, the best path from an NM perspective
would be a supplicant per-network property that would then be sent for
CONNECT-capable drivers, or which the supplicant would manually handle
for softmac drivers through its existing AP selection code.

Dan

quoted

details can be configured for a connection and the bss selection
parameters could be one of those. What level of detail would be
needed
there. Not saying we can not have more detail in the nl80211 API.

quoted

quoted

I guess we have two different designs, one where the roaming
logic is in
firmware and other where wpasupplicant is responsible for this.
(And I
assume that brcfmac belongs to the former group.) Ideally it
would be
nice that we would have a same configuration knob for both but I
don't
know if that's really feasible.

Both of these would work as long as wpa_supplicant has means for
providing such configuration to the driver in a generic manner.
That
NL80211_CMD_CONNECT extension with a new optional attribute would
be
such a generic design.

So does the driver need to advertise support for bss selection
parameters or can it simply ignore the parameters. Assuming the
latter
for now.

Regards,
Arend
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