On 2015/11/19 14:45, Yuanhan Liu wrote: > On Thu, Nov 19, 2015 at 02:14:13PM +0900, Tetsuya Mukawa wrote: >> On 2015/11/19 12:33, Yuanhan Liu wrote: >>> On Thu, Nov 19, 2015 at 12:13:38PM +0900, Tetsuya Mukawa wrote: >>>> On 2015/11/19 11:18, Yuanhan Liu wrote: >>>>> On Thu, Nov 19, 2015 at 11:03:50AM +0900, Tetsuya Mukawa wrote: >>>>>> On 2015/11/17 22:29, Yuanhan Liu wrote: >>>>>>> On Fri, Nov 13, 2015 at 02:20:30PM +0900, Tetsuya Mukawa wrote: >>>>>>>> These variables are needed to be able to manage one of virtio devices >>>>>>>> using both vhost library APIs and vhost PMD. >>>>>>>> For example, if vhost PMD uses current callback handler and private >>>>>>>> data >>>>>>>> provided by vhost library, A DPDK application that links vhost library >>>>>>>> cannot use some of vhost library APIs. >>>>>>> Can you be more specific about this? >>>>>>> >>>>>>> --yliu >>>>>> How about like below? >>>>>> >>>>>> commit log: >>>>>> Currently, when virtio device is created and destroyed, vhost library >>>>>> will call one of callback handlers. >>>>>> The vhost PMD need to use this pair of callback handlers to know which >>>>>> virtio devices are connected actually. >>>>>> Because we can register only one pair of callbacks to vhost library, if >>>>>> the PMD use it, DPDK applications >>>>>> cannot have a way to know the events. >>>>> Will (and why) the two co-exist at same time? >>>> Yes it is. Sure, I will describe below in commit log. >>>> >>>> Because we cannot map some of vhost library APIs to ethdev APIs, in some >>>> cases, we still >>>> need to use vhost library APIs for a port created by the vhost PMD. One >>>> of example is >>>> rte_vhost_enable_guest_notification(). >>> I don't get it why it has something to do with a standalone PMD callback. >>> And if you don't call rte_vhost_enable_guest_notification() inside vhost >>> PMD, where else can you call that? I mean, you can't start vhost-pmd >>> and vhost-swithc in the mean time, right? >> No it's not true, even after connecting to virtio-net device, you can >> change the flag. >> It's just a hint for virtio-net driver, and it will be used while queuing. >> (We may be able to change the flag, even while sending or receiving packets) >> >>> And, pmd callback and the old notify callback will not exist at same >>> time in one case, right? If so, why is that needed? >>> >>> BTW, if it's a MUST, would you provide a specific example? >> Actually, this patch is not a MUST. >> >> But still the users need callback handlers to know when virtio-net >> device is connected or disconnected. >> This is because the user can call rte_vhost_enable_guest_notification() >> only while connection is established. > What does "the user" mean? Is there a second user of vhost lib besides > vhost PMD, that he has to interact with those connected devices? If so, > how?
Sorry, my English is wrong. Not a second user. For example, If DPDK application has a port created by vhost PMD, then needs to call rte_vhost_enable_guest_notification() to the port. DPDK application needs to know when virtio-net device is connected or disconnected, because the function is only valid while connecting. But without callback handler, DPDK application cannot know it. This is what I wanted to explain. Thanks, Tetsuya > --yliu >> Probably we can use link status changed callback of the PMD for this >> purpose. >> (The vhost PMD will notice DPDK application using link status callback) >> >> But I am not sure whether we need to implement link status changed >> callback for this purpose. >> While processing this callback handler, the users will only calls vhost >> library APIs that ethdev API cannot map, or store some variables related >> with vhost library. >> If so, this callback handler itself is specific for using vhost library. >> And it may be ok that callback itself is implemented as one of vhost >> library APIs. >> >> Tetsuya >> >>> --yliu >>>> Thanks, >>>> Tetsuya >>>> >>>> >>>>> --yliu >>>>> >>>>>> This may break legacy DPDK >>>>>> applications that uses vhost library. >>>>>> To prevent it, this patch adds one more pair of callbacks to vhost >>>>>> library especially for the vhost PMD. >>>>>> With the patch, legacy applications can use the vhost PMD even if they >>>>>> need additional specific handling >>>>>> for virtio device creation and destruction. >>>>>> For example, legacy application can call >>>>>> rte_vhost_enable_guest_notification() in callbacks to change setting. >>>>>> >>>>>> Tetsuya
