Re: [dpdk-dev] [PATCH 03/14] eal/common: introduce union rte_device and related

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, Jan 04, 2016 at 09:08:15PM +0100, Jan Viktorin wrote:
> The union rte_device can be used in situations where we want to work with all
> devices without distinguishing among bus-specific features (PCI, ...).
> The target device type can be detected by reading the magic.
> 
> Also, the macros RTE_DEVICE_DECL and RTE_DEVICE_PTR_DECL are introduced to
> provide a generic way to declare a device or a pointer to a device. The macros
> aim to preserve API backwards-compatibility. Eg.
> 
> struct old_super_struct {             =>   struct old_super_struct {
>     struct rte_pci_device *pci_dev;   =>        RTE_DEVICE_PTR_DECL(pci_dev);
>     ...                               =>       ...
> };                                    =>   };
> 
> struct old_super_struct inst;
> 
> The new code should reference inst.dev.pci, the old code can still use the
> inst.pci_dev. The previously introduced magic is included so one can ask the
> instance about its type:
> 
> if (inst.dev.magic == RTE_PCI_DEVICE_MAGIC) {
>     ...
> }

Rather than magic numbers i.e. #defines, an enum might be better.

/Bruce