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

[谢华伟(此时此刻）]

On 2021/1/21 23:38, Maxime Coquelin wrote:
>> Do you mean we apply or abandon patch 3? I am both OK. The first
>> priority to me is to enable MMIO bar support.
> OK, so yes, I think we should abandon patch 2 and patch 3.
> For patch 1, it looks valid to me, but I'll let Ferruh decide.
>
> For your device, if my understanding is correct, what we need to do is
> to support MMIO for legacy devices. Correct?
yes.
> If so, the change should be in virtio_pci.c. In vtpci_init(), after
> modern detection has failed, we should check the the BAR is PIO or MMIO
> based on the flag. the result can be saved in struct virtio_pci_dev.
>
>
> We would introduce new wrappers like vtpci_legacy_read,
> vtpci_legacy_write that would either call rte_pci_ioport_read,
> rte_pci_ioport_read in case of PIO, or rte_read32, rte_write32 in case
> of MMIO.

There are two choices.

1, apply patch 2.

     IO/MMIO port are mapped and accessed using the same API. Kernel is 
doing in the same way like the following.

             io_addr = pci_iomap

                 get PIO directly or ioremap

             iowrite16/32(val, io_addr + offset)

I think applying patch 2 is a correct choice. It is a fix. Driver had 
better not know if bar is PIO or MMIO.  ioport in ioport_xx API means 
IO, not PIO.

Btw, it only affects virtio PMD,  not that intrusive.

  2, virtio specific change to enable MMIO support.

Comparing with choice 1, i feels it is not that clean and pretty.

>
> 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
>