Re: [PATCH v2 3/3] virtio: Add a new layer to abstract pci access method

On 2016/01/29 18:17, Yuanhan Liu wrote:

On Thu, Jan 28, 2016 at 06:33:32PM +0900, Tetsuya Mukawa wrote:

quoted

This patch addss function pointers to abstract pci access method.
This abstraction layer will be used when virtio-net PMD supports
container extension.

The below functions abstract how to access to pci configuration space.

struct virtio_pci_cfg_ops {
        int   (*map)(...);
        void  (*unmap)(...);
        void *(*get_mapped_addr)(...);
        int   (*read)(...);
};

The pci configuration space has information how to access to virtio
device registers. Basically, there are 2 ways to acccess to the
registers. One is using portio and the other is using mapped memory.
The below functions abstract this access method.

One question: is there a way to map PCI memory with Qtest? I'm thinking
if we can keep the io_read/write() for Qtest as well, if so, code could
be simplified, a lot, IMO.

Yes, I agree with you.
But AFAIK, we don't have a way to mmap it from DPDK application.

We may be able to map PCI configuration space to a memory address space
that guest CPU can handle.
But even in this case, I guess we cannot access the memory without qtest
messaging.

Thanks,
Tetsuya