[dpdk-dev] [PATCH] doc: plan splitting the ethdev ops struct

Ferruh Yigit ferruh.yigit at intel.com
Fri Feb 21 11:40:00 CET 2020

On 2/18/2020 6:01 AM, Stephen Hemminger wrote:
> On Mon, 17 Feb 2020 15:38:05 +0000
> Ferruh Yigit <ferruh.yigit at intel.com> wrote:
>> For the ABI compatibility it is better to hide internal data structures
>> from the application as much as possible. But because of some inline
>> functions 'struct eth_dev_ops' can't be hidden completely.
>> Plan is to split the 'struct eth_dev_ops' into two as ones used by
>> inline functions and ones not used, and hide the second part that not
>> used by inline functions completely to the application.
>> Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
>> ---
>> Cc: David Marchand <david.marchand at redhat.com>
>> Cc: Thomas Monjalon <thomas at monjalon.net>
>> Cc: Andrew Rybchenko <arybchenko at solarflare.com>
>> ---
>>  doc/guides/rel_notes/deprecation.rst | 6 ++++++
>>  1 file changed, 6 insertions(+)
>> diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
>> index dfcca87ab..2aa431028 100644
>> --- a/doc/guides/rel_notes/deprecation.rst
>> +++ b/doc/guides/rel_notes/deprecation.rst
>> @@ -72,6 +72,12 @@ Deprecation Notices
>>    In 19.11 PMDs will still update the field even when the offload is not
>>    enabled.
>> +* ethdev: Split the ``struct eth_dev_ops`` struct to hide it as much as possible.
>> +  Currently the ``struct eth_dev_ops`` struct is accessible by the application
>> +  because some inline functions, like ``rte_eth_tx_descriptor_status()``,
>> +  access the struct directly. The struct will be separate in two, the ops used
>> +  by inline functions still will be accessible to user but rest will be hidden.
>> +
>>  * cryptodev: support for using IV with all sizes is added, J0 still can
>>    be used but only when IV length in following structs ``rte_crypto_auth_xform``,
>>    ``rte_crypto_aead_xform`` is set to zero. When IV length is greater or equal
> Good luck, truely hiding internals is hard. The mbuf structure is already split but not really
> hidden at all (just look at dwarf output). It doesn't make sense to do it unless
> you can really hide it.

I believe this can be done, only following [1] dev_ops are used by inline
functions, rest can be moved into separate struct and moved into ethdev driver
looking header.


> I would attack the rte_device stuff first. Make rte_device opaque to the application
> that would help for future versions. Then work backwards to rte_tehtdev.

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