From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932099Ab1KRQLM (ORCPT ); Fri, 18 Nov 2011 11:11:12 -0500 Received: from acsinet15.oracle.com ([141.146.126.227]:42418 "EHLO acsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753769Ab1KRQLJ (ORCPT ); Fri, 18 Nov 2011 11:11:09 -0500 Message-ID: <4EC6837F.1050201@oracle.com> Date: Sat, 19 Nov 2011 00:10:39 +0800 From: annie li Organization: Oracle Corporation User-Agent: Thunderbird 1.5.0.9 (Windows/20061207) MIME-Version: 1.0 To: Ian Campbell CC: Konrad Rzeszutek Wilk , "jeremy@goop.org" , "xen-devel@lists.xensource.com" , "kurt.hackel@oracle.com" , "linux-kernel@vger.kernel.org" , Paul Durrant Subject: Re: [Xen-devel] Re: [PATCH 2/3] xen/granttable: Grant tables V2 implementation References: <4EC3B62F.6080702@oracle.com> <1321451372-13596-1-git-send-email-annie.li@oracle.com> <4EC62FE5.2080608@oracle.com> <1321614166.3664.311.camel@zakaz.uk.xensource.com> <20111118135221.GC12433@phenom.dumpdata.com> <1321624845.3664.354.camel@zakaz.uk.xensource.com> In-Reply-To: <1321624845.3664.354.camel@zakaz.uk.xensource.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: ucsinet22.oracle.com [156.151.31.94] X-CT-RefId: str=0001.0A090202.4EC68399.0087,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2011-11-18 22:00, Ian Campbell wrote: > On Fri, 2011-11-18 at 13:52 +0000, Konrad Rzeszutek Wilk wrote: > >>>> + xen_raw_printk(str); >>>> + panic(str); >>>> >>> I expect you've just copied this style from elsewhere but I really >>> dislike this duplication of prints. If panic is not useful here we >>> really ought to address that at the root instead of going around >>> patching things to print every panic message twice. I thought >>> earlyprintk was supposed to solve this problem. Perhaps a generic >>> early_panic_print could be added to the panic code? >>> >> We are using this combo in swiotlb-xen and as well in the xen pci. >> We could declere a 'xen_raw_panic' that would do the job? >> >> The problem is that panic() uses the "late" printk mechanism (so >> it goes through the buffer that ends up not beign flushed) and the >> panic never sees the light. >> > > So lets fix that instead of working around it... > > >> The 'xen_raw_printk' is synchronous.. >> >> But I wonder if the panic surfaces if 'earlyprintk=xen' is used? >> At which point it might be that the those extra xen_raw_printk >> become pointless? >> > > I think panic's do come out with earlyprintk (unless they are truly > super early). > So we have two candidates: xen_raw_printk + panic panic + earlyprintk=xen If panic does work with earlyprintk, then the latter one is better. Otherwise, there will be duplicated string printed out with 'earlyprintk=xen'. Thanks Annie > Ian. > > > >