[dpdk-dev] [PATCH v5 3/3] PCI: don't use vfio ioctl call to access PIO resource

[Ferruh Yigit]

On 1/27/2021 2:43 PM, 谢华伟(此时此刻） wrote:
> 
> On 2021/1/27 18:32, Ferruh Yigit wrote:
>> I was waiting for clarification if this can be solved in virtio, which seems 
>> clarified and decided to go with this patch, I am OK to proceed with patch 1 & 2.
>>
>> But first patch changes how PIO address get, it changes the Linux interface 
>> used to get the PIO.
>> And as far as I can see second patch requires this new interface to be able to 
>> access the MEM resources.
>>
>> I have a concern that this interface change may cause issues with various 
>> distros, kernel versions etc.. And prefer it goes through a full -rc1 
>> validation cycle.
>>
>> Huawei, I am aware the patch is around for a while but to play safe, I suggest 
>> considering it for early next release, so it can be tested enough, instead of 
>> getting if for -rc2/3 in this release.
>>
>> Thanks,
>> ferruh
>>
> Hi Ferruh and Maxime:
> 
> igb_uio kernel driver gets resource through pci_resource_start, i.e, 
> (dev)->resource[(bar)].start
> 
> uio_pci_generic and the generic way in my patch 1 gets resource through the same 
> interface:
> 
>          pci dev driver exports to userspace the bar resource attributes through 
> pci_dev->resource (check resource_show in kernel's drivers/pci/pci-sysfs.c)
> 
> Other arch than x86 uses the same interface in their pci_uio_ioport_map.
> 
> So patch 1 is the most generic way and shouldn't break things. /proc/ioports 
> should be fully dropped.
> 
> Using /proc/ioport is partly my fault at the very beginning. It causes so much 
> mess.
> 
> Could you please confirm this?
> 

Hi Huawei,

I confirm that interface is already in use, 'pci_parse_sysfs_resource()' does 
similar parsing.

Most probably it is safe as you and Maxime said, and I am not trying to be 
difficult but extra conscious here.

Will it cause too much trouble to consider the patch early next release? This 
gives more time and testing after the patch merged.

Thanks,
ferruh

> Thanks huawei
> 
>>> Could you please post v6?
>>>
>>> Thanks,
>>> Maxime
>>>
>>>>>
>>>>> It is not too late for this release, as the change will not be that
>>>>> intrusive. But if you prepare such patch, please base it on top of my
>>>>> virtio rework series; To make it easier to you, I added it to the dpdk-
>>>>> next-virtio tree:
>>>>> https://git.dpdk.org/next/dpdk-next-virtio/log/?h=virtio_pmd_rework_v2
>>>>>
>>>>> Thanks,
>>>>> Maxime
>>>>>
>>>>