From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olaf Hering Subject: Re: [PATCH] linux-2.6.18/xencons: generalize use of add_preferred_console() Date: Fri, 7 Feb 2014 11:07:33 +0100 Message-ID: <20140207100733.GA1958@aepfle.de> References: <52AAE1C2020000780010CE39@nat28.tlf.novell.com> <20140206225334.GA21743@aepfle.de> <52F4A4F7020000780011A102@nat28.tlf.novell.com> <20140207083234.GA17978@aepfle.de> <52F4B1A7020000780011A14B@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WBiLU-0000Rc-T0 for xen-devel@lists.xenproject.org; Fri, 07 Feb 2014 10:07:41 +0000 Content-Disposition: inline In-Reply-To: <52F4B1A7020000780011A14B@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel , Ian Campbell List-Id: xen-devel@lists.xenproject.org On Fri, Feb 07, Jan Beulich wrote: > >>> On 07.02.14 at 09:32, Olaf Hering wrote: > > On Fri, Feb 07, Jan Beulich wrote: > > > >> They question is what the intended behavior here is: I'd generally > > > > In my opinion dom0 is just a child of Xen, which should follow the rules > > of the parent. If Xen is configured to have its console on serial then > > the default of dom0 should be to follow just that. Appearently its just > > a matter of correctly using xvc0. > > > > I'm not sure what the gain would be to have Xen on serial and dom0 > > somewhere else, and enforcing the need of a console= cmdline option to > > point dom0 also to serial. Thats just doing things twice. > > That's a fair point, but leaves aside the case of Xen _not_ using > the serial console. Dom0 has no way to know, and hence would > still push output there, not knowing that it ends up no-where. You mean no Xen console= option implies that dom0 writes no-where? I would think dom0 will use the graphics card in this case to send its output. > Also the "follow the rules of the parent" already doesn't apply for > the VGA console case, where Dom0 makes its own decision too > (and it's for that reason that Xen needs to stop sending data to > the VGA in order to not interfere). Hence I'm not sure that > argument really counts. The details about driving a certain hardware dont really matter. I think the important part is "goes to the wire" vs. "goes to the monitor". I think the bug is that register_console("xvc") is called without a preceeding add_prefered_console, which with current kernels means a second entry in /proc/consoles. This in turn lets systemd spawn a login for that. Somehow I think the rules have changed since 2.6.18. I will have a look at this now. Olaf