From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57033) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ehICp-0000ca-F4 for qemu-devel@nongnu.org; Thu, 01 Feb 2018 11:59:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ehICl-00075w-LD for qemu-devel@nongnu.org; Thu, 01 Feb 2018 11:59:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46832) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ehICl-00074d-F3 for qemu-devel@nongnu.org; Thu, 01 Feb 2018 11:59:19 -0500 Date: Thu, 1 Feb 2018 18:59:07 +0200 From: "Michael S. Tsirkin" Message-ID: <20180201185830-mutt-send-email-mst@kernel.org> References: <20180131230607-mutt-send-email-mst@kernel.org> <20180131233422.GP26425@localhost.localdomain> <20180201040608-mutt-send-email-mst@kernel.org> <8dbc7c99-84f6-0023-526b-359fdf2b5162@redhat.com> <20180201121009.GR26425@localhost.localdomain> <20180201150254-mutt-send-email-mst@kernel.org> <20180201163132.GV26425@localhost.localdomain> <20180201184655-mutt-send-email-mst@kernel.org> <20180201165739.GY26425@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180201165739.GY26425@localhost.localdomain> Subject: Re: [Qemu-devel] [PATCH V8 1/4] mem: add share parameter to memory-backend-ram List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: Marcel Apfelbaum , qemu-devel@nongnu.org, cohuck@redhat.com, f4bug@amsat.org, yuval.shaia@oracle.com, borntraeger@de.ibm.com, pbonzini@redhat.com, imammedo@redhat.com On Thu, Feb 01, 2018 at 02:57:39PM -0200, Eduardo Habkost wrote: > On Thu, Feb 01, 2018 at 06:48:54PM +0200, Michael S. Tsirkin wrote: > > On Thu, Feb 01, 2018 at 02:31:32PM -0200, Eduardo Habkost wrote: > > > On Thu, Feb 01, 2018 at 04:24:30PM +0200, Michael S. Tsirkin wrote: > > > [...] > > > > The full fix would be to allow QEMU to map a list of > > > > pages to a guest supplied IOVA. > > > > > > Thanks, that's what I expected. > > > > > > While this is not possible, the only requests I have for this > > > patch is that we clearly document: > > > * What's the only purpose of share=on on a host-memory-backend > > > object (due to pvrdma limitations). > > > * The potential undesirable side-effects of setting share=on. > > > * On the commit message and other comments, clearly distinguish > > > HVAs in the QEMU address-space from IOVAs, to avoid confusion. > > > > Looking forward, when we do support it, how will management find out > > it no longer needs to pass the share parameter? > > > > Further, if the side effects of the share parameter go away, > > how will it know these no longer hold? > > A query-host-capabilities or similar QMP command seems necessary > for that. Is anyone working on that? > It would be useful for other stuff like MAP_SYNC. > -- > Eduardo