From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH 9/9] xenstore: when running in mini-os use printk for diagnostic messages Date: Tue, 15 Dec 2015 12:52:08 +0000 Message-ID: <1450183928.16856.175.camel@citrix.com> References: <1449848861-7700-1-git-send-email-jgross@suse.com> <1449848861-7700-10-git-send-email-jgross@suse.com> <1450182665.16856.165.camel@citrix.com> <56700BE7.40800@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56700BE7.40800@suse.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: Juergen Gross , xen-devel@lists.xen.org, ian.jackson@eu.citrix.com, stefano.stabellini@eu.citrix.com, wei.liu2@citrix.com List-Id: xen-devel@lists.xenproject.org On Tue, 2015-12-15 at 13:47 +0100, Juergen Gross wrote: > On 15/12/15 13:31, Ian Campbell wrote: > > On Fri, 2015-12-11 at 16:47 +0100, Juergen Gross wrote: > > > Xenstore messages for diagnostic purposes are lost today in case > > > xenstore is running under mini-os instead in a dom0 daemon. > > > > Where does vfprintf end up under mini-os? > > TBH: I just couldn't find it. I tried to get some diagnostics when > I started this work and couldn't find any place where the messages > would occur. > > > > Use printk of mini-os in this situation. > > > > and this now ends up on the console and (for a debug h/v) in the xen > > dmesg, > > is that right? > > The console of the xenstore domain seems to be a little bit special, as > there is no component up to now writing the information needed to > connect xenconsoled to the xenstore domain. This could be the reason I > wasn't able to see any message printed via vfprintf. :-( That sounds probable. > So in the end it will be part of xen dmesg. Only for a debug=y Xen, not for a release build IIRC, unless you added some other privilege along with your new flag which I missed. > And this is where it should > be, as such messages will be needed in case of xenstore domain not > working properly. And I think it's console can be accessed by any means > only in case of a working xenstore. :-) An alternative would be init-xenstore-domain to daemonize and take on respoibility for consuming the console ring and throwing it into a file? Ian.