From owner-freebsd-current@FreeBSD.ORG Mon Jun 26 00:38:00 2006 Return-Path: X-Original-To: current@FreeBSD.org Delivered-To: freebsd-current@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 660BE16A400; Mon, 26 Jun 2006 00:38:00 +0000 (UTC) (envelope-from maksim.yevmenkin@savvis.net) Received: from mta11.adelphia.net (mta11.adelphia.net [68.168.78.205]) by mx1.FreeBSD.org (Postfix) with ESMTP id E3A954478D; Mon, 26 Jun 2006 00:37:59 +0000 (GMT) (envelope-from maksim.yevmenkin@savvis.net) Received: from [192.168.1.236] (really [70.32.199.60]) by mta11.adelphia.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20060626003758.GWOD23502.mta11.adelphia.net@[192.168.1.236]>; Sun, 25 Jun 2006 20:37:58 -0400 Message-ID: <449F2CE0.3030403@savvis.net> Date: Sun, 25 Jun 2006 17:40:00 -0700 From: maksim yevmenkin User-Agent: Thunderbird 1.5.0.4 (Windows/20060516) MIME-Version: 1.0 To: current@FreeBSD.org References: <449EAED3.7000706@root.org> <449F18D9.2000109@FreeBSD.org> <449EB711.30509@root.org> <449F1ACF.5060101@FreeBSD.org> In-Reply-To: <449F1ACF.5060101@FreeBSD.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Maxim Sobolev , Nate Lawson Subject: Re: kbdmux support for ddb and mountroot? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Jun 2006 00:38:00 -0000 Maxim Sobolev wrote: > Nate Lawson wrote: >> Maxim Sobolev wrote: >>> Works here to specify alternate root just fine. I am missing something? >>> >>> -Maxim >>> >>> Nate Lawson wrote: >>>> kbdmux does not currently support ddb and mountroot in both -current >>>> and 6-stable. This means that if you get a panic, no backtrace or >>>> other interaction is possible. Also, if your /etc/fstab is wrong, >>>> no way to specify an alternate root. >>>> >>>> Are there any plans to improve this? What needs to be completed to >>>> get back to previous support for these features? >>>> >>>> Thanks, >> >> I'm using a PS/2 keyboard on one machine (RELENG_6) and a built-in >> PS/2 keyboard on my laptop. Neither register any keystrokes in DDB or >> with alternate root unless I disable kbdmux with the tunable. > > USB keyboard works just fine here (7-CURRENT) for alternate root > selection via kbdmux. I don't know if there are some differences in > kbdmux behavior between RELENG_6 and HEAD. yes, there is a known problem with atkbd(4) keyboards and kbdmux(4) with ddb, geli, mountroot etc. i believe that atkbd(4) does not handle "polled" mode correctly. when system drops into ddb interrupts are disabled, atkbd(4) interrupt handler is not called and thus kbdmux(4) is not getting any input from slave atkbd(4) keyboard. i'm not convinced that this is kbdmux(4) bug. i think that its the job of the low level keyboard driver to deal with "polled" mode correctly. a while ago, i sent (to current@) a quick and dirty hack (patch) for atkbd(4) to work around this problem, i.e. poll i/o ports and call interrupt handler if there is a char pending. that works fine with kbdmux(4), atkbd(4) and ddb, geli etc. however, this hack introduces a regression, i.e. when kbdmux(4) in NOT enabled, atkbd(4) often generates duplicate chars when in ddb mode. so, i believe that atkbd(4) must be enhanced to properly deal with "polled" mode (i.e. when interrupts are disabled). ukbd(4), for example, does this, and, there is no such problem with kbdmux(4) and ukbd(4). unfortunately, due to the office move, i've temporarily lost all my test/development boxes. thanks, max