[dpdk-dev] [PATCH v2 4/4] add ABI checks

[Thomas Monjalon]

04/02/2020 16:52, Trahe, Fiona:
> 
> > We are working on a patch, when it is ready we will send it.
> > If it's not ready by end of your today, of course, go ahead with (b) and
> > we will work towards 20.05.
> 
> We will not be sending a patch today.
> The patch we're working on will provide two versions of rte_cryptodev_info_get(),
> both call the same PMD function from the dev_ops info_get fn ptr.
> The default version operates s as normal, the 19.11 version searches
> through the list returned by the PMD, looking for sym.aead.algo = ChaChaPoly, it needs to strip it from the list.
> As PMDs just pass a ptr to their capabilities list ( it isn't a linked list, but an array
> with an end marker  = RTE_CRYPTODEV_END_OF_CAPABILITIES_LIST) if the API
> layer detects Chacha it must allocate some space and store a local copy of the
> trimmed list. This must be stored only once per device.

I don't understand what you have to store.
Can't you just set the algo to 0 if it is ChaCha?

> This versioning will apply to any PMD which wants to take advantage of the new API between now and 20.11.
> 
> Note, I expect the ABI checker tools will still complain of ABI breakage as the LIST_END value will still change.

Right, you need to update the ignore list for the tool.

> We are also reviewing all other cryptodev APIs in case there is any other API which needs versioning.
>  
> Anyone see any problem with this approach?

The other issue is with all other functions accepting this enum as input.
We should continue returning an error if getting Chacha as input with
19.11 version of these functions.
But I would tend to consider this small ABI breakage can be ignored
as it is in the error path.