From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43799) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZnBo5-00034a-Ri for qemu-devel@nongnu.org; Fri, 16 Oct 2015 16:40:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZnBo1-00066y-Mz for qemu-devel@nongnu.org; Fri, 16 Oct 2015 16:40:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37514) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZnBo1-00066u-HP for qemu-devel@nongnu.org; Fri, 16 Oct 2015 16:40:49 -0400 References: <561D2966.9070007@m2r.biz> <561D3513.8060005@redhat.com> From: John Snow Message-ID: <562160CC.8050204@redhat.com> Date: Fri, 16 Oct 2015 16:40:44 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefano Stabellini Cc: Anthony.Perard@citrix.com, Fabio Fantoni , "qemu-devel@nongnu.org" , "xen-devel@lists.xen.org" On 10/13/2015 01:10 PM, Stefano Stabellini wrote: > On Tue, 13 Oct 2015, John Snow wrote: >> On 10/13/2015 11:55 AM, Fabio Fantoni wrote: >>> I added ahci disk support in libxl and using it for week seems that was >>> ok, after a reply of Stefano Stabellini seems that xen disk unplug >>> support only ide disks: >>> http://git.qemu.org/?p=qemu.git;a=commitdiff;h=679f4f8b178e7c66fbc2f39c905374ee8663d5d8 >>> >>> Today Paul Durrant told me that even if pv disk is ok also with ahci and >>> the emulated one is offline can be a risk: >>> http://lists.xenproject.org/archives/html/win-pv-devel/2015-10/msg00021.html >>> >>> >>> I tried to take a fast look in qemu code but I not understand the needed >>> thing for add the xen disk unplug support also for ahci, can someone do >>> it or tell me useful information for do it please? >>> >>> Thanks for any reply and sorry for my bad english. >>> >> >> I'm not entirely sure what features you need AHCI to support in order >> for Xen to be happy. >> >> I'd guess hotplugging, but where I get confused is that IDE disks don't >> support hotplugging either, so I guess I'm not sure sure what you need. >> >> Stefano, can you help bridge my Xen knowledge gap? > > Hi John, > > we need something like hw/i386/xen/xen_platform.c:unplug_disks but that > can unplug AHCI disk. And by unplug, I mean "make disappear" like > pci_piix3_xen_ide_unplug does for ide. > I'm trying to follow this discussion as best as I am able, but my lack of experience with Xen prevents me from really participating in a meaningful way. (I see that Laszlo is still discussing some CD-ROM issues with Fabio which may be of interest to me...) At any rate, I won't be authoring any Xen-specific hacks to the AHCI device, but I do have plans to implement hot-plugging emulation as per the AHCI spec. Perhaps this is sufficient for the Xen layer, but someone else will need to author the appropriate glue code. If "real" hot-plugging is not sufficient, we'll need to discuss further, preferably over some RFC patches. Thanks, --js