From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuanhan Liu Subject: Re: [PATCH 1/4] vhost: handle VHOST_USER_SET_LOG_BASE request Date: Wed, 2 Dec 2015 22:31:01 +0800 Message-ID: <20151202143101.GR2325@yliu-dev.sh.intel.com> References: <1449027793-30975-1-git-send-email-yuanhan.liu@linux.intel.com> <1449027793-30975-2-git-send-email-yuanhan.liu@linux.intel.com> <565EF7E9.6080400@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: dev@dpdk.org, Victor Kaplansky , "Michael S. Tsirkin" To: Panu Matilainen , Thomas Monjalon Return-path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id CC8D658DB for ; Wed, 2 Dec 2015 15:27:39 +0100 (CET) Content-Disposition: inline In-Reply-To: <565EF7E9.6080400@redhat.com> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Wed, Dec 02, 2015 at 03:53:45PM +0200, Panu Matilainen wrote: > On 12/02/2015 05:43 AM, Yuanhan Liu wrote: > >VHOST_USER_SET_LOG_BASE request is used to tell the backend (dpdk > >vhost-user) where we should log dirty pages, and how big the log > >buffer is. > > > >This request introduces a new payload: > > > > typedef struct VhostUserLog { > > uint64_t mmap_size; > > uint64_t mmap_offset; > > } VhostUserLog; > > > >Also, a fd is delivered from QEMU by ancillary data. > > > >With those info given, an area of memory is mmaped, assigned > >to dev->log_base, for logging dirty pages. > > > >Signed-off-by: Yuanhan Liu > >--- > > lib/librte_vhost/rte_virtio_net.h | 2 ++ > > lib/librte_vhost/vhost_user/vhost-net-user.c | 7 ++++- > > lib/librte_vhost/vhost_user/vhost-net-user.h | 6 ++++ > > lib/librte_vhost/vhost_user/virtio-net-user.c | 44 +++++++++++++++++++++++++++ > > lib/librte_vhost/vhost_user/virtio-net-user.h | 1 + > > 5 files changed, 59 insertions(+), 1 deletion(-) > > > >diff --git a/lib/librte_vhost/rte_virtio_net.h b/lib/librte_vhost/rte_virtio_net.h > >index 5687452..416dac2 100644 > >--- a/lib/librte_vhost/rte_virtio_net.h > >+++ b/lib/librte_vhost/rte_virtio_net.h > >@@ -127,6 +127,8 @@ struct virtio_net { > > #define IF_NAME_SZ (PATH_MAX > IFNAMSIZ ? PATH_MAX : IFNAMSIZ) > > char ifname[IF_NAME_SZ]; /**< Name of the tap device or socket path. */ > > uint32_t virt_qp_nb; /**< number of queue pair we have allocated */ > >+ uint64_t log_size; /**< Size of log area */ > >+ uint8_t *log_base; /**< Where dirty pages are logged */ > > void *priv; /**< private context */ > > struct vhost_virtqueue *virtqueue[VHOST_MAX_QUEUE_PAIRS * 2]; /**< Contains all virtqueue information. */ > > } __rte_cache_aligned; > > This (and other changes in patch 2 breaks the librte_vhost ABI > again, so you'd need to at least add a deprecation note to 2.2 to be > able to do it in 2.3 at all according to the ABI policy. I was thinking that adding a new field (instead of renaming it or removing it) isn't an ABI break. So, I was wrong? > > Perhaps a better option would be adding some padding to the structs > now for 2.2 since the vhost ABI is broken there anyway. That would > at least give a chance to keep it compatible from 2.2 to 2.3. It will not be compatible, unless we add exact same fields (not something like uint8_t pad[xx]). Otherwise, the pad field renaming is also an ABI break, right? Thomas, should I write an ABI deprecation note? Can I make it for v2.2 release If I make one tomorrow? (Sorry that I'm not awared of that it would be an ABI break). --yliu