[dpdk-dev] [RFC PATCH 0/5] rework feature enabling macros for compatibility
Ferruh Yigit
ferruh.yigit at intel.com
Wed Sep 30 18:12:50 CEST 2020
On 9/16/2020 5:44 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
+1 to all X_PMD macros.
>
> * 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.
>
Why we need this backward compatibility? The macros are to enable/disable a
module, so isn't it DPDK internal.
If we enable the macros for new naming convention and update the build system
and code for new macros, will it affect the end user?
>
> * 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_ at 0@'
> drivers/bus/meson.build:config_flag_fmt = 'RTE_LIBRTE_ at 0@_BUS'
> drivers/common/meson.build:config_flag_fmt = 'RTE_LIBRTE_ at 0@_COMMON'
> drivers/compress/meson.build:config_flag_fmt = 'RTE_LIBRTE_PMD_ at 0@'
> drivers/crypto/meson.build:config_flag_fmt = 'RTE_LIBRTE_PMD_ at 0@'
> drivers/event/meson.build:config_flag_fmt = 'RTE_LIBRTE_PMD_ at 0@_EVENTDEV'
> drivers/mempool/meson.build:config_flag_fmt = 'RTE_LIBRTE_ at 0@_MEMPOOL'
> drivers/net/meson.build:config_flag_fmt = 'RTE_LIBRTE_ at 0@_PMD'
> drivers/raw/meson.build:config_flag_fmt = 'RTE_LIBRTE_PMD_ at 0@_RAWDEV'
> drivers/regex/meson.build:config_flag_fmt = 'RTE_LIBRTE_ at 0@_PMD'
> drivers/vdpa/meson.build:config_flag_fmt = 'RTE_LIBRTE_ at 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
> 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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