Hi Shahaf, On Wed, Oct 23, 2019 at 12:00:30PM +0000, Shahaf Shuler wrote: > Hi Olivier, > > Thursday, October 17, 2019 5:42 PM, Olivier Matz: > > Subject: [dpdk-dev] [PATCH v2] mbuf: support dynamic fields and flags > > > > Many features require to store data inside the mbuf. As the room in mbuf > > structure is limited, it is not possible to have a field for each feature. > > Also, > > changing fields in the mbuf structure can break the API or ABI. > > > > This commit addresses these issues, by enabling the dynamic registration of > > fields or flags: > > > > - a dynamic field is a named area in the rte_mbuf structure, with a > > given size (>= 1 byte) and alignment constraint. > > - a dynamic flag is a named bit in the rte_mbuf structure. > > > > The typical use case is a PMD that registers space for an offload feature, > > when the application requests to enable this feature. As the space in mbuf > > is > > limited, the space should only be reserved if it is going to be used (i.e > > when > > the application explicitly asks for it). > > According to description, the dynamic field enables custom application and > supported PMDs to use the dynamic part of the mbuf for their specific needs. > However the mechanism to report and activate the field/flag registration > comes from the general OFFLOAD flags. > > Maybe it will be better to an option to query and select dynamic fields for > PMD outside of the standard ethdev offload flags?
It is not mandatory to use the ethdev layer to register a dynamic field or flag in the mbuf. It is just the typical use case. It can also be enabled when using a library that have specific needs, for instance, you call rte_reorder_init(), and it will register the sequence number dynamic field. An application that requires a specific mbuf field can also do the registration by itself. In other words, when you initialize a subpart that needs a dynamic field or flag, you have to do the registration there. > > > > > The registration can be done at any moment, but it is not possible to > > unregister fields or flags for now. > > > > Signed-off-by: Olivier Matz <olivier.m...@6wind.com> > > Acked-by: Thomas Monjalon <tho...@monjalon.net>
