From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52151) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wws9q-00052d-K7 for qemu-devel@nongnu.org; Tue, 17 Jun 2014 08:06:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wws9j-0005fx-8E for qemu-devel@nongnu.org; Tue, 17 Jun 2014 08:06:34 -0400 Received: from cantor2.suse.de ([195.135.220.15]:58401 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wws9j-0005fS-1G for qemu-devel@nongnu.org; Tue, 17 Jun 2014 08:06:27 -0400 Message-ID: <53A02F41.7000908@suse.de> Date: Tue, 17 Jun 2014 14:06:25 +0200 From: Alexander Graf MIME-Version: 1.0 References: <1402933252-1079-1-git-send-email-ming.lei@canonical.com> <1402933252-1079-3-git-send-email-ming.lei@canonical.com> <20140616180447.3346dbb2.cornelia.huck@de.ibm.com> <20140617090741.0c5a4b4b.cornelia.huck@de.ibm.com> <20140617104615.10fc3946.cornelia.huck@de.ibm.com> <20140617122521.13c6342b.cornelia.huck@de.ibm.com> <20140617140413.42c0b518.cornelia.huck@de.ibm.com> In-Reply-To: <20140617140413.42c0b518.cornelia.huck@de.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/4] s390-virtio-bus: move common virtio properties to virtio s390 device class List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck , Ming Lei Cc: Peter Maydell , qemu-devel@nongnu.org, Paolo Bonzini On 17.06.14 14:04, Cornelia Huck wrote: > On Tue, 17 Jun 2014 18:45:09 +0800 > Ming Lei wrote: > >> On Tue, Jun 17, 2014 at 6:40 PM, Ming Lei wrote: >>> On Tue, Jun 17, 2014 at 6:25 PM, Cornelia Huck wrote: >>>> On Tue, 17 Jun 2014 18:15:39 +0800 >>>> Ming Lei wrote: >>>> >>>>> On Tue, Jun 17, 2014 at 4:46 PM, Cornelia Huck wrote: >>>>>>> Looks like s390 virtio-blk never enables the two common features, is >>>>>>> there any reason the two features can't be supported by s390? >>>>>> Indirect descriptors are fine. event_idx will not work IIUC because we >>>>>> always need to do a sync before we see changes, and this needs an >>>>>> interrupt to trigger. >>>>> Sounds like the old s390 isn't cache coherent? Because you mean >>>>> write in one side can only be observed from another side with an >>>>> explicit notification or interrupt. >>>>> >>>>> On arm/arm64, we didn't see any problem with event_idx. >>>> But you probably have the queues in guest memory, as on other >>>> transports (including virtio-ccw)? The old s390-virtio transport keeps >>>> the devices and their virtqueues in a memory area behind the guest >>>> memory - the guest does not see that memory directly, but a sync has to >>>> be performed to see virtqueue movement (see s390_virtio_device_sync()). >>> OK, it looks like a real physical device, :-) >>> >>> I will keep s390-virtio as it is, thanks for your explanation. >> BTW, do you want me to add DEFINE_VIRTIO_COMMON_FEATURES() >> to s390_virtio_net_properties and s390_virtio_scsi_properties since >> I remove them from their default properties? > It might be better to remove them for good :) > > Nobody has probably tried to use them for some time... > I just start a very minimal guest with a virtio-console and a > virtio-blk device. Don't know whether Alex has a more advanced setup > at hand? It's the only target that works with TCG, no? Alex