Re: [dpdk-dev] [PATCH] bus/pci: optimize pci device probe

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

On 5/6/20 8:43 AM, Jerin Jacob wrote:
> On Wed, May 6, 2020 at 12:05 PM Maxime Coquelin
> <maxime.coquelin@redhat.com> wrote:
>>
>> Hi,
>>
>> On 5/5/20 6:16 PM, David Marchand wrote:
>>> On Tue, May 5, 2020 at 5:50 PM Jerin Jacob <jerinjacobk@gmail.com> wrote:
>>>>>>
>>>>>> Removing this special case could break x86 applications running with
>>>>>> legacy virtio.
>>>>>>
>>>>>>
>>>>>> On the plus side, we have been announcing for some time in virtio:
>>>>>> RTE_PMD_REGISTER_KMOD_DEP(net_virtio, "* igb_uio | uio_pci_generic | vfio-pci");
>>>>>
>>>>> What is to conclude?
>>>>> # The In-tree virtio driver uses ""* igb_uio | uio_pci_generic |
>>>>> vfio-pci"" driver as backend and it does not need RTE_KDRV_NONE?
>>>>> OR
>>>>> # The in-tree, legacy virtio(const struct virtio_pci_ops legacy_op)
>>>>> can work without any kernel driver in the backend. So RTE_KDRV_NONE
>>>>> need?
>>>>
>>>> Ping. What is the conclusion? If it is former then this patch is valid.
>>>
>>> I am fine with dropping the legacy part, but I wanted to hear from
>>> Maxime at least.
>>>
>>>
>>
>> IIUC, it means that with Jerin patch, Virtio Legacy devices support will
>> be dropped as they won't be probed anymore?
> 
> The device drivers with RTE_KDRV_NONE as the backend will not be probed.
> 1) Are Virtio Legacy devices are type of RTE_KDRV_NONE?

Virtio Legacy devices can be probed with no kernel driver.

> 2) if yes, Would you like to support for virtio legacy device?

I am OK to remove legacy + RTE_KDRV_NONE case, but I think it needs an
announcement and being done in a later release to let end-users using
that configuration time to do the change.

> 3) if yes, Please fix RTE_PMD_REGISTER_KMOD_DEP(net_virtio, "* igb_uio
> | uio_pci_generic | vfio-pci");

While support gets removed, what about:

RTE_PMD_REGISTER_KMOD_DEP(net_virtio, "* igb_uio | uio_pci_generic |
vfio-pci | none"); ?

Maxime