On 09/04/2015 05:51 PM, Doug Ledford wrote:
> On 09/04/2015 05:32 PM, Jason Gunthorpe wrote:
>> On Fri, Sep 04, 2015 at 05:17:38PM -0400, Doug Ledford wrote:
>>> + /*
>>> + * In order to maintain backward/forward binary compatibility
>>> + * with libmlx4-1.0.6, which has the original version of the
>>> + * flow steering patches, we need to set the two
>>> + * ABI_compat_placeholder entries to match the driver
>>> + * set flow entries. This is because, in the specific instance
>>> + * of using libmlx4-1.0.6 with the fixed version of
>>> + * libibvberbs, the ibv_create_flow inline function already
>>> + * compiled into libmlx4-1.0.6 will be loooking in the
>>> + * ABI_placeholder spots for the function pointer to the
>>> + * create and destroy flow verbs.
>>> */
>>
>> This isn't quite the right comment, it has very little to do with mlx,
>> ibv_create_flow is the user entry point, the above applies to
>> everything linked to ibverbs.
>
> You're right. I'll correct that.
The new cokment:
/*
* In order to maintain backward/forward binary
compatibility
* with apps compiled against libibverbs-1.1.8 that use the
* flow steering addition, we need to set the two
* ABI_placeholder entries to match the driver set flow
* entries. This is because apps compiled against
* libibverbs-1.1.8 use an inline ibv_create_flow and
* ibv_destroy_flow function that looks in the placeholder
* spots for the proper entry points. For apps compiled
* against libibverbs-1.1.9 and later, the inline functions
* will be looking in the right place.
*/
>> My suggestion was to not change the ibverbs->user ABI at all and just
>> mangle the driver side, ie move the ABI_placeholder to what was drv_
>> instead of lib_.
>
> As you pointed out, this doesn't make the entire matrix of old/new
> driver/libibverbs/app work. I can think of two things that would be
> ugly about doing it this way if we wanted to make that matrix fully
> operational. With the way I did it, things are clean in the new driver
> and mostly clean in the new libibverbs, and the full matrix works.
>
>> Can't see anything wrong with it this way, off hand, other than the
>> comment.
>
> Thanks for looking at it ;-)
>
--
Doug Ledford <dledford@xxxxxxxxxx>
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