Re: [dpdk-dev] [PATCH 04/13] eal: introduce driver type

[Jan Blunck <jblunck@infradead.org>]

On Mon, Dec 19, 2016 at 10:59 PM, Stephen Hemminger
<stephen@networkplumber.org> wrote:
> Since multiple buses and device types need to be supported.
> Provide type field in driver.
> ---
>  lib/librte_eal/common/include/rte_dev.h  | 15 ++++++++++++---
>  lib/librte_eal/common/include/rte_pci.h  |  1 +
>  lib/librte_eal/common/include/rte_vdev.h |  1 +
>  3 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/lib/librte_eal/common/include/rte_dev.h b/lib/librte_eal/common/include/rte_dev.h
> index e5471a22..3f4e26e6 100644
> --- a/lib/librte_eal/common/include/rte_dev.h
> +++ b/lib/librte_eal/common/include/rte_dev.h
> @@ -144,12 +144,21 @@ void rte_eal_device_insert(struct rte_device *dev);
>  void rte_eal_device_remove(struct rte_device *dev);
>
>  /**
> + * Type of device driver
> + */
> +enum rte_driver_type {
> +       PMD_VIRTUAL,
> +       PMD_PCI,
> +};
> +
> +/**
>   * A structure describing a device driver.
>   */
>  struct rte_driver {
>         TAILQ_ENTRY(rte_driver) next;  /**< Next in list. */
> -       const char *name;                   /**< Driver name. */
> -       const char *alias;              /**< Driver alias. */
> +       const char *name;              /**< Driver name. */
> +       const char *alias;             /**< Driver alias. */
> +       enum rte_driver_type type;     /**< Driver type. */
>  };

I wonder who is the user of the type. It can't be the driver itself
because it must be aware of what kind of low-level interface it
serves. So this seems to be a helper to allow users of rte_driver to
upcast to the object that embeds the rte_driver at runtime. I don't
believe that this is a good interface because it often leads to ugly
and error prone code.

>
>  /**
> @@ -243,4 +252,4 @@ __attribute__((used)) = str
>  }
>  #endif
>
> -#endif /* _RTE_VDEV_H_ */
> +#endif /* _RTE_DEV_H_ */
> diff --git a/lib/librte_eal/common/include/rte_pci.h b/lib/librte_eal/common/include/rte_pci.h
> index 9ce88472..d377d539 100644
> --- a/lib/librte_eal/common/include/rte_pci.h
> +++ b/lib/librte_eal/common/include/rte_pci.h
> @@ -492,6 +492,7 @@ RTE_INIT(pciinitfn_ ##nm); \
>  static void pciinitfn_ ##nm(void) \
>  {\
>         (pci_drv).driver.name = RTE_STR(nm);\
> +       (pci_drv).driver.type = PMD_PCI; \
>         rte_eal_pci_register(&pci_drv); \
>  } \
>  RTE_PMD_EXPORT_NAME(nm, __COUNTER__)
> diff --git a/lib/librte_eal/common/include/rte_vdev.h b/lib/librte_eal/common/include/rte_vdev.h
> index 784e837d..98fb5bb5 100644
> --- a/lib/librte_eal/common/include/rte_vdev.h
> +++ b/lib/librte_eal/common/include/rte_vdev.h
> @@ -88,6 +88,7 @@ static void vdrvinitfn_ ##vdrv(void)\
>  {\
>         (vdrv).driver.name = RTE_STR(nm);\
>         (vdrv).driver.alias = vdrvinit_ ## nm ## _alias;\
> +       (vdrv).driver.type = PMD_VIRTUAL;\
>         rte_eal_vdrv_register(&vdrv);\
>  } \
>  RTE_PMD_EXPORT_NAME(nm, __COUNTER__)
> --
> 2.11.0
>