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* [dpdk-dev] [RFC PATCH 0/5] rework feature enabling macros for compatibility
@ 2020-09-16 16:44 Bruce Richardson
  2020-09-16 16:44 ` [dpdk-dev] [RFC PATCH 1/5] app: fix missing dependencies Bruce Richardson
                   ` (11 more replies)
  0 siblings, 12 replies; 82+ messages in thread
From: Bruce Richardson @ 2020-09-16 16:44 UTC (permalink / raw)
  To: david.marchand; +Cc: dev, Bruce Richardson

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'

* 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

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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