On Wed, Sep 30, 2020 at 05:12:50PM +0100, Ferruh Yigit wrote: > 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? >
I'd love to be able to just take this option, but the macros are used to indicate to applications what drivers or other components can be expected to be available - much as the case for testpmd. Ideally, they should not be necessary. I think the best approach is that proposed earlier on this thread - we keep backward compatibility as much as possible in this release, but add in a new set of standardized macros and a deprecation notice about the old ones. I hope to work on a new rev of this patchset shortly. /Bruce
