Message-ID: <b25312890812072302iaa5b84y1abe590c36d44d50@mail.gmail.com> (sfid-20081208_080305_284624_E3639C8E)
Date: Mon, 8 Dec 2008 09:02:52 +0200
From: "Rami Rosen" <roszenrami@gmail.com>
To: "Dan E" <trg_info@mailhaven.com>
Subject: Re: Userspace tools: Roadmap?
Cc: linux-wireless@vger.kernel.org
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Hello,

> will hostapd be re-written to speak
> nl/cfg80211, or is a new config tool needed?

  Just one little thing, regarding hostapd:

You can use hostapd with nl80211.

Adding this entry:
 driver=nl8021
to hostapd.conf will cause it to work with nl80211 API
(driver_nl80211.c)

You should also build hostapd with
CONFIG_DRIVER_NL80211 set in the Makefile.

This is a known way to work with hostapd and master mode; see for example,
http://acx100.erley.org/nl80211_master_mode.html

(BTW, I am using the latest git of hostapd, but it could be relevant
also for older versions).

Regarding iw:  I think that adding support for changing
channel in iw is possible and that there is no inherent reason not to
do so. Are there any other things you should do with iw which do not
exist (and exist with iwcofig) ?

Regards,
Rami Rosen


On Mon, Dec 8, 2008 at 1:29 AM, Dan E <trg_info@mailhaven.com> wrote:
> Looking at some of the Linux Wireless website pages it appears as though
> "iw" is meant to be the successor to the older pre-mac80211 userspace
> tools.  In that category we have ifconfig, iproute2, iwconfig and
> iwpriv.  For an AP there's also hostapd and wpa_supplicant.  Probably
> some others I've missed, not to mention Network Manager.  I can see how
> configuration and setup wouldn't necessarily be limited to "iw" using
> nl/cfg80211, but in the short term is that the tool of choice for
> migrating the functionality of the old tools to the new mac80211
> infrastructure?
>
> Here's my situation: I'm developing a driver for an old 80211 b/g
> chipset.  It's ancient by modern standards.  It operates only in the 2.4
> GHz band, it doesn't have any mesh capabilities, it has a "broken"
> EEPROM, it supports only single RX and TX queues, and it's an ASIC
> design that doesn't use firmware.  It has no "turbo" modes.  The company
> that manufactured it went bust in 2005.  It was used in a wide array of
> soho routers and access points several years ago but never caught on as
> a very popular" chip.
>
> I want to write, from scratch, a mac80211 driver for this chipset using
> information I've gained over the last few years from specs and reverse
> engineering the binary-only driver that shipped with it (with a Linux
> 2.4.18 kernel).  I have the framework of the driver set up and working.
> It loads, detects and initializes the hardware on the PCI bus, reads the
> hardware MAC address, sets up the TX and RX queues, and registers with
> the mac80211 stack.  I see devices wmaster0 and wlan0 when I modprobe
> the driver.  So far, so good.  Eventually I want to support AP and
> MONITOR modes, too, but STA mode seems to be in a more advanced state
> right now so I am starting with that.
>
> Userspace tools.  I want to proceed as if Wireless Extensions never
> existed.  Is that even possible?  For instance, how do I command a
> channel change from userspace?  iw doesn't have that.  Should it?  Or do
> I need to drop back to iwconfig?  Is iw the preferred command-line way
> to do everything the old tools did, but using nl/cfg80211 instead of
> ioctls?  When we get to AP mode, will hostapd be re-written to speak
> nl/cfg80211, or is a new config tool needed?  The same questions apply
> to wpa_supplicant.
>
> In general, what's the way forward for new userspace tools?  nl80211 and
> cfg80211 are a given, I understand that, but what's the recommended
> approach from the perspective of a developer looking to make a clean
> break from Wireless Extensions with a new cleanroom driver written from
> scratch with no pre-existing baggage to worry about?  Start making
> additions to iw's capabilities?  Adapt some other existing tool to use
> nl/cfg80211, or write something completely new?
>
> I've been following linux wireless developments since the big Summit of
> '06, but this is my first attempt at jumping in.  Getting a handle on
> the "big picture view" of what everything is going to look like when
> mac80211 is a mature implementation is a bit difficult.  I've noticed a
> lot of recent changes to the Linux Wireless website.  All good stuff but
> not very comprehensive in scope.  I realize nobody likes to write
> documentation :)
>
> If somone could answer only 1 question (okay, it's a two-parter) the one
> I would most like answered is this:  How does one, from userspace, ask
> the driver to switch to a specific channel, and what callback(s) from
> mac80211 should my driver expect to receive as a result?  I think my
> driver can handle the task of changing the channel on the hardware and
> manage all the housekeeping that goes along with that; I just don't get
> how to issue that command from userspace.
>
> TIA for any help, advice, pointers, flames, etc.
>
> --
> Dan
>
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