From: Marcel Holtmann <marcel@holtmann.org>
To: Brian Norris <briannorris@chromium.org>
Cc: Johannes Berg <johannes@sipsolutions.net>,
Matthew Wang <matthewmwang@google.com>,
linux-wireless <linux-wireless@vger.kernel.org>,
Kirtika Ruchandani <kirtika@google.com>, Jouni Malinen <j@w1.fi>
Subject: Re: Flag for detecting 802.11r Fast BSS Transition support
Date: Sat, 17 Aug 2019 15:40:36 +0200 [thread overview]
Message-ID: <7CCE8D56-9E1A-4E04-9C28-E384C1B2E2EA@holtmann.org> (raw)
In-Reply-To: <CA+ASDXNC0hwFzSTvZmUq-B7r_H+pZ3N=p_kjfMqKb1gftsmDKw@mail.gmail.com>
Hi Brian,
>>> Well, I guess we could just run the command and look for EOPNOTSUPP...
>>
>> this kind of API design and usage is bad. Try-and-error approach is just not sustainable.
>
> Sure. That "suggestion" was quite literally an afterthought. Not
> really a proper suggestion.
>
>> Even while it is late to add a proper flag that indicates support, we need to do this to make nl80211 better for the future.
>
> I suppose. I'm not quite sure how I would make use of that properly
> though, given the corpus of kernels out there where the flag doesn't
> exist (but the feature does). Some other heurestic for determining
> kernel recency? Compile-time flags for the relevant user space, such
> that one builds it for "new kernel API (w/ flag)" vs. "old kernel API"
> (with the latter not even trying to look for the flag)?
>
> Or I guess a more proactive approach: implement both a "supported" and
> an "unsupported" flag, so user space can figure out a tristate: flag
> not available (old kernel -- user space is left to guess) vs. command
> supported flag vs. command not supported flag.
>
> That seems a bit awkward though.
I would not make it this complicated. Add the flag for future kernels and the move on with life. Trying to workaround older versions is something I would not bother with. It is always possible to backport the feature to older kernels. And if you have a distribution or an OEM that cares, then that is what is going to happen.
Regards
Marcel
next prev parent reply other threads:[~2019-08-17 13:40 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-04 19:06 Flag for detecting 802.11r Fast BSS Transition support Matthew Wang
2019-04-03 21:02 ` Brian Norris
2019-04-08 19:52 ` Johannes Berg
2019-08-08 17:15 ` Brian Norris
2019-08-16 18:54 ` Marcel Holtmann
2019-08-16 20:29 ` Brian Norris
2019-08-17 13:40 ` Marcel Holtmann [this message]
2019-08-21 16:54 ` Brian Norris
2019-08-21 16:59 ` Marcel Holtmann
2019-08-21 8:03 ` Johannes Berg
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