Re: [dpdk-dev] [PATCH v2] common/mlx5: add provider query port support to glue library

Hi David,

-----Original Message-----
From: David Marchand <redacted>
Sent: Wednesday, June 23, 2021 13:43
To: Slava Ovsiienko <redacted>
Cc: dev <redacted>; Raslan Darawsheh <redacted>; Matan
Azrad [off-list ref]; NBU-Contact-Thomas Monjalon
[off-list ref]; dpdk stable [off-list ref]
Subject: Re: [dpdk-dev] [PATCH v2] common/mlx5: add provider query port
support to glue library

On Sat, Jun 19, 2021 at 2:49 PM Viacheslav Ovsiienko
[off-list ref] wrote:

quoted

The rdma-core mlx5 provider introduced the port attributes query API
since version v35.0 - the mlx5dv_query_port routine. In order to
support this change in the rdma-core the conditional compilation flag
HAVE_MLX5DV_DR_DEVX_PORT_V35 is introduced by the this patch.

In the OFED rdma-core version the new compatible mlx5dv_query_port
routine was introduced as well, replacing the existing proprietary
mlx5dv_query_devx_port routine. The proprietary routine was controlled
in PMD code with HAVE_MLX5DV_DR_DEVX_PORT conditional flag.

Currently, the OFED rdma-core library contains both versions of port
query API. And this version is a transitional one, there are the plans
to remove the proprietary mlx5dv_query_devx_port routine and the
HAVE_MLX5DV_DR_DEVX_PORT flag in PMD will not work anymore.

We had one more dependency on this flag in the code (for the
mlx5dv_dr_action_create_dest_ib_port routine) and the patch fixes
mentioned dependency also, by introducing the new dedicated
conditional flag - HAVE_MLX5DV_DR_CREATE_DEST_IB_PORT.

This patch is highly desirable to be provided in DPDK LTS releases due
to it covers the major compatibility issue.

This patch is a fix, yet nothing tells this story in the title.

This patch is not a fix. Actually it covers the compatibility issue, not a bug.
The Upstream rdma-core was evolved, its community adopted a
slightly different API version than was presented in the vendor version.
Our PMD should conform both versions and we provided this patch for DPDK.

And the title does not reflect that it is a fix wrt versions of rdma-core.
Is this a build issue? or a runtime compat issue?

It is not a build because we have conditional compilation and we can
build PMD, but functionality is affected in severe way.

A good title makes life easier for users and people maintaining stable versions
of DPDK.

I'm in contact with LTS maintainers about the patch,
the title should not be a problem.

Anyway, if you prefer the title be changed to one with "fix" word -
please, let me know, I'll provide the update. 

With best regards,
Slava