Re: [dpdk-dev] management of non-PCI devices

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 23 Jul 2015 17:42:58 +0200
Thomas Monjalon <thomas.monjalon@6wind.com> wrote:

> As noticed when reviewing the changes for hotplugging ring PMD,
> 	http://dpdk.org/ml/archives/dev/2015-July/021872.html
> a driver is considered in ethdev and EAL as a PCI driver:
> 
>  * Each Ethernet driver acts as a PCI driver and is represented by a generic
>  * *eth_driver* structure that holds:
>  * - An *rte_pci_driver* structure (which must be the first field).
>  * - The *eth_dev_init* function invoked for each matching PCI device.
>  * - The *eth_dev_uninit* function invoked for each matching PCI device.
>  * - The size of the private data to allocate for each matching device.
>  */
> struct eth_driver {                                                                                              
>     struct rte_pci_driver pci_drv;    /**< The PMD is also a PCI driver. */
>     eth_dev_init_t eth_dev_init;      /**< Device init function. */
>     eth_dev_uninit_t eth_dev_uninit;  /**< Device uninit function. */
>     unsigned int dev_private_size;    /**< Size of device private data. */
> };
> 
> So the non PCI drivers don't use rte_eth_driver_register().
> Then a difference is made with these flags:
> enum pmd_type {
>     PMD_VDEV = 0,
>     PMD_PDEV = 1,
> };
> 
> With this kind of weird things:
> static struct rte_driver rte_virtio_driver = {
>     .type = PMD_PDEV,                                                                                            
>     .init = rte_virtio_pmd_init,
> };
> Because virtio is a virtual device with a virtual PCI address.
> 
> All these things are not normal and make EAL code more and more difficult to
> maintain. That's why we must stop accepting new code using these workarounds
> and start working on a refactoring.
> 
> Comments welcome

The hyper-v driver which was posted here added a new bus type (vmbus)
and it was not too painful. There were minimal changes to base EAL to
make a union where pci_drv is used.