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

[Jan Viktorin <viktorin@rehivetech.com>]

On Wed, 13 Jan 2016 14:01:19 +0000
Bruce Richardson <bruce.richardson@intel.com> wrote:

> 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.

True. However, would it be helpful to put really some _magic_ numbers
there for debugging purposes (to clearly recognize the data type)? Or,
is it sufficient to just say 1 for PCI, 2 for SoC, 3 for xxx...?

> 
> /Bruce
> 



-- 
   Jan Viktorin                  E-mail: Viktorin@RehiveTech.com
   System Architect              Web:    www.RehiveTech.com
   RehiveTech
   Brno, Czech Republic