From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail2.candelatech.com ([208.74.158.173]:54936 "EHLO mail2.candelatech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752082AbbBWRnm (ORCPT ); Mon, 23 Feb 2015 12:43:42 -0500 Message-ID: <54EB66CC.1030800@candelatech.com> (sfid-20150223_184345_307787_75924070) Date: Mon, 23 Feb 2015 09:43:40 -0800 From: Ben Greear MIME-Version: 1.0 To: Johannes Berg CC: linux-wireless@vger.kernel.org Subject: Re: [RFC] mac80211_hwsim: notify user-space about channel change. References: <1424217588-29558-1-git-send-email-greearb@candelatech.com> (sfid-20150218_005956_617537_D2A9B91F) <1424692155.2782.6.camel@sipsolutions.net> In-Reply-To: <1424692155.2782.6.camel@sipsolutions.net> Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 02/23/2015 03:49 AM, Johannes Berg wrote: > On Tue, 2015-02-17 at 15:59 -0800, greearb@candelatech.com wrote: >> From: Ben Greear >> >> The goal is to allow the user-space application to properly >> filter packets before sending them down to the kernel. This >> should more closely mimic what a real piece of hardware would >> do. > >> + * @HWSIM_CMD_NOTIFY: notify user-space about driver changes. This is >> + * designed to help the user-space app better emulate radio hardware. >> + * This command uses: >> + * %HWSIM_ATTR_FREQ # Notify current operating center frequency. >> + * %HWSIM_ATTR_ADDR_TRANSMITTER # ID which radio we are notifying about. >> * @__HWSIM_CMD_MAX: enum limit > > This seems a bit strange - don't we already tag packets with the > frequency? Why would you need the channel change separately? What does > that even mean? Depending on how you use this it could entirely break > off-channel operation, for example. I was thinking about passive scans. In that case, we would not always get a packet transmitted when the channel changes? I was thinking user-space would mimic a real radio that can only listen on one channel at once (can any real radios actually listen on two channels at once?) So, if we are off-channel, and pkt arrives for the 'main' channel, then a real radio should drop it, right? Of course, if user-space does not care, then it can simply ignore the channel-change logic so I think this would be backwards compat with existing hwsim user-space apps. Thanks, Ben > > johannes > -- Ben Greear Candela Technologies Inc http://www.candelatech.com