On 9/16/20 7:44 PM, Bruce Richardson wrote:
As flagged previously on-list, there are a number of macros used to specify
what libs and drivers are enabled in the build which differ from the
equivalents used with make. This patchset is one possible approach to
fixing these, but as part of the investigation some issues were hit where
I'd like additional input to ensure we are ok with the approach taken in
this set.

First, a problem statement:

* While the make build defines generally followed a pattern, there were
   many instances where the defines were unique. These can be seen in the
   values defined in patch 4.

* The NIC PMDs had two separate standards for the defines - some (the
   physical device drivers) tended to have the _PMD at the end of the
   macros, while the virtual drivers had it in the middle. Since the
   majority seemed to go with it at the end, meson chose this option.
   However, as can be seen from patch 4, a number now need special handling
   for compatibility

* This "_PMD" at the end made its way into other device classes, such as
   crypto and event, but it appears that the standard for these classes from
   make is in fact the opposite. Therefore we have had for the last 2+ years
   conflicting macros for crypto, compression and event classes.

* There is also the question of how important compatibility for these
   macros is, especially since we have had numerous incompatibilities
   without it being reported before. There is also the issue of the
   deprecation process for macros, since these are not part of any ABI.

What's done in this set:

* Firstly, and missing dependencies on apps or examples had to be fixed,
   where a dependency was missed because it was never needed due to the code
   being stripped out because of a missing macro.

* Secondly, since it is likely that use of the defines from make is more
   widespread than those from meson, the defines for the crypto, compression
   and event classes are changed to align with the make values. Just in case
   though, temporary code is added to drivers/meson.build to redefine the
   old meson values too, and a deprecation notice is added for these. The
   hope is that we can then remove this temporary code in the next release,
   leaving us with just one macro style for each driver class.

* Thirdly, we add an additional set of backward compatibility macros for
   the ~30 special-cases, where the meson macro template does not match that
   defined for make. Again, this is intended to be temporary and a
   deprecation notice is given for the macros in that file.

* Finally, we replace all instances of the old macros in the codebase with
   the newer versions. While the work done in the first four patches (steps
   1-3 above) should be ok to backport, this final patch is not suitable for
   backporting. However, it is relatively simple to produce a new patch for
   backporting which allow either old or new values to be used in macros.


Open issues/considerations after this patch:

* We still have inconsistencies in our driver macro and naming templates.
   This is just a nice-to-have, but if people are ok with generally having a
   breakage in our macro defines, we could clean this up a lot further.
   Notice how 'net', 'regex' and 'vdpa' have '_PMD' at the end, while most
   others have it before the name. Notice also that many device classes have
   the class at the end of the template, while bbdev has it in the middle.
        $ git grep config_flag_fmt -- drivers/*/meson.build
        drivers/baseband/meson.build:config_flag_fmt = 
'RTE_LIBRTE_PMD_BBDEV_@0@'
        drivers/bus/meson.build:config_flag_fmt = 'RTE_LIBRTE_@0@_BUS'
        drivers/common/meson.build:config_flag_fmt = 'RTE_LIBRTE_@0@_COMMON'
        drivers/compress/meson.build:config_flag_fmt = 'RTE_LIBRTE_PMD_@0@'
        drivers/crypto/meson.build:config_flag_fmt = 'RTE_LIBRTE_PMD_@0@'
        drivers/event/meson.build:config_flag_fmt = 
'RTE_LIBRTE_PMD_@0@_EVENTDEV'
        drivers/mempool/meson.build:config_flag_fmt = 'RTE_LIBRTE_@0@_MEMPOOL'
        drivers/net/meson.build:config_flag_fmt = 'RTE_LIBRTE_@0@_PMD'
        drivers/raw/meson.build:config_flag_fmt = 'RTE_LIBRTE_PMD_@0@_RAWDEV'
        drivers/regex/meson.build:config_flag_fmt = 'RTE_LIBRTE_@0@_PMD'
        drivers/vdpa/meson.build:config_flag_fmt = 'RTE_LIBRTE_@0@_PMD'

As a generic direction I would vote for standard names which are
based on directory structure:
 - RTE_LIBRTE_ETHDEV
 - RTE_DRIVER_NET_SFC
 - RTE_DRIVER_COMMON_MLX5
 - RTE_DRIVER_BUS_PCI

* Are we ok to remove the older macros after one release of deprecation, or
   do we need to wait to next API window.

* I have not made any changes to the docs for this, since I expect that
   these macros are already covered by the doc changes in the make removal
   set.

Reviews and comments welcome.

Bruce Richardson (5):
   app: fix missing dependencies
   examples/l2fwd-crypto: fix missing dependency
   meson: fix compatibility with make build defines
   build: add defines for compatibility with make build
   build: replace use of old build macros

  app/test-crypto-perf/meson.build     |   3 +
  app/test-pmd/cmdline.c               |   8 +-
  app/test-pmd/meson.build             |  12 +++
  app/test-pmd/parameters.c            |  12 +--
  app/test-pmd/testpmd.c               |  24 ++---
  app/test-pmd/testpmd.h               |   4 +-
  app/test/meson.build                 |   3 +
  app/test/test_eal_flags.c            |   4 +-
  config/meson.build                   |   3 +-
  config/rte_compatibility_defines.h   | 129 +++++++++++++++++++++++++++
  config/rte_config.h                  |   1 +
  doc/guides/rel_notes/deprecation.rst |  17 ++++
  drivers/compress/meson.build         |   2 +-
  drivers/crypto/meson.build           |   2 +-
  drivers/event/meson.build            |   2 +-
  drivers/meson.build                  |  15 ++++
  examples/l2fwd-crypto/meson.build    |   3 +
  17 files changed, 214 insertions(+), 30 deletions(-)
  create mode 100644 config/rte_compatibility_defines.h


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