Re: [dpdk-dev] [PATCH v2] vhost: add virtio configuration space messages

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 03/28/2018 11:33 AM, Maxime Coquelin wrote:
> 
> 
> On 03/28/2018 11:19 AM, Wodkowski, PawelX wrote:
>>> -----Original Message-----
>>> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]
>>> Sent: Wednesday, March 28, 2018 11:12 AM
>>> To: Kulasek, TomaszX <tomaszx.kulasek@intel.com>; yliu@fridaylinux.org
>>> Cc: Verkamp, Daniel <daniel.verkamp@intel.com>; Harris, James R
>>> <james.r.harris@intel.com>; Wodkowski, PawelX
>>> <pawelx.wodkowski@intel.com>; dev@dpdk.org; Liu, Changpeng
>>> <changpeng.liu@intel.com>; Tan, Jianfeng <jianfeng.tan@intel.com>
>>> Subject: Re: [dpdk-dev] [PATCH v2] vhost: add virtio configuration space
>>> messages
>>>
>>>
>>>
>>> On 03/27/2018 05:35 PM, Tomasz Kulasek wrote:
>>>> This patch adds new vhost user messages GET_CONFIG and SET_CONFIG used
>>>> for get/set virtio device's configuration space.
>>>>
>>>> Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
>>>> Signed-off-by: Tomasz Kulasek <tomaszx.kulasek@intel.com>
>>>> ---
>>>> Changes in v2:
>>>>    - code cleanup
>>>>
>>>>    lib/librte_vhost/rte_vhost.h  |  4 ++++
>>>>    lib/librte_vhost/vhost_user.c | 22 ++++++++++++++++++++++
>>>>    lib/librte_vhost/vhost_user.h | 16 ++++++++++++++++
>>>>    3 files changed, 42 insertions(+)
>>>>
>>>> diff --git a/lib/librte_vhost/rte_vhost.h 
>>>> b/lib/librte_vhost/rte_vhost.h
>>>> index d332069..fe30518 100644
>>>> --- a/lib/librte_vhost/rte_vhost.h
>>>> +++ b/lib/librte_vhost/rte_vhost.h
>>>> @@ -84,6 +84,10 @@ struct vhost_device_ops {
>>>>        int (*new_connection)(int vid);
>>>>        void (*destroy_connection)(int vid);
>>>>
>>>> +    int (*get_config)(int vid, uint8_t *config, uint32_t config_len);
>>>> +    int (*set_config)(int vid, uint8_t *config, uint32_t offset,
>>>> +            uint32_t len, uint32_t flags);
>>>> +
>>>>        void *reserved[2]; /**< Reserved for future extension */
>>>
>>> You are breaking the ABI, as you grow the size of the ops struct.
>>>
>>> Also, I'm wondering if we shouldn't have a different ops for external
>>> backends. Here these ops are more intended to the application, we could
>>> have a specific ops struct for external backends IMHO.
>>
>> What do mean by "external backends" ?
> 
> Libs like SPDK or Crypto that implements their own ring processing,
> comparing to an application like DPDK that doesn't care of rings
> details.

Sorry, I meant comparing to an application like OVS*