From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: [PATCH 9/9] xenstore: when running in mini-os use printk for diagnostic messages Date: Tue, 15 Dec 2015 13:55:59 +0100 Message-ID: <56700DDF.5030105@suse.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> <1450183928.16856.175.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1450183928.16856.175.camel@citrix.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: Ian Campbell , 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 15/12/15 13:52, Ian Campbell wrote: > 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. No, this is correct. >> 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? Interesting idea. I'll try this. Juergen