Hi Adrien, > On Tue, May 14, 2019 at 08:58:42AM +0000, Smoczynski, MarcinX wrote: > > > > Hey Konstantin, > > > > > > > > On Mon, May 13, 2019 at 10:49:00AM +0000, Ananyev, Konstantin wrote: > > > > > Hi Adrien, > > > > > > > > > > > > > > > > > On Mon, May 13, 2019 at 09:51:24AM +0000, Smoczynski, MarcinX > > > wrote: > > > > > > > 10/05/2019 20:17, Thomas Monjalon: > > > > > > > > 10/05/2019 19:14, Smoczynski, MarcinX: > > > > > > > > > To summarize we have different visibility sets for Linux and > > > > > > > > > BSD when using XOPEN_SOURCE or POSIX_C_SOURCE explicitly. > > > To > > > > > > > > > overcome this situation we can either remove problematic > > > > > > > > > XOPEN macros from mk/meson rules (drivers/net/failsafe, > > > > > > > > > drivers/net/mlx4, > > > > > > > > > drivers/net/mlx5) > > > > > > > > > > > > > > > > What is the consequence of removing these macros in mlx and > > > failsafe PMDs? > > > > > > > > > > > > > > The purpose of these *_SOURCE constants is to enable particular > > > > > > > feature sets visibility. As long as we have GNU_SOURCE on Linux > > > > > > > removing it won't have any consequences. On BSD it will unify > > > > > > > feature sets visibility with the rest of sources. Can't think of > > > > > > > any > > > downsides here. > > > > > > > > > > > > > > I believe XOPEN_SOURCE was introduced to extend features not to > > > restrict them. > > > > > > > > > > > > I confirm that under Linux, all IPPROTO_* (POSIX/XOPEN/RFC1700) > > > > > > are defined regardless (_GNU_SOURCE not even needed), while under > > > > > > FreeBSD, the non-POSIX versions are only defined when > > > __BSD_VISIBLE is set. > > > > > > > > > > > > The FreeBSD behavior is more correct in this respect since the > > > > > > purpose of _XOPEN_SOURCE and friends is also to let applications > > > > > > limit the risk of redefinitions in case they were written for an > > > > > > earlier standard (e.g. -D_XOPEN_SOURCE=500 vs. - > > > D_XOPEN_SOURCE=600). > > > > > > > > > > Still not sure why do you need it for failsafe and mlx PMDs? > > > > > Would something in these PMDs be broken without '- > > > D_XOPEN_SOURCE=600'? > > > > > > > > Well, not really. At least not anymore if they compile fine without it > > > > on all supported targets. I don't mind if they are removed from PMDs. > > > > > > > > _XOPEN_SOURCE=600 was originally added to mlx4 (later inherited by > > > > mlx5 and > > > > failsafe) for the following reasons: > > > > > > > > - Out fo habit, since a lot of stuff in unistd.h and fcntl.h depends on > > > > it > > > > to be exposed. Some affected definitions were likely needed at some > > > point. > > > > > > > > - Besides toggling C syntax extensions, forcing a C standard through the > > > > -std parameter (e.g. -std=c99) in order to guarantee a minimum level > > > > of > > > > C compliance disables the implicit presence of nonstandard > > > > definitions, > > > > which must be re-enabled as needed through the appropriate #defines. > > > > > > > > For instance, including unistd.h for getsid() stops working as soon as > > > > you use -std=c99. On Linux you can get it back through -std=gnu99 or > > > > by combining -std=c99 with -D_GNU_SOURCE or -D_XOPEN_SOURCE. The > > > > latter was chosen because it is the standard define supposed to work > > > across OSes. > > > > > > > > Historically mlx4 had to enable -std=c99 to be able to use various > > > > features not present when GCC defaulted to -std=gnu90. It was later > > > > transformed to > > > > -std=c11 for similar reasons (anonymous members in structs/unions if > > > > memory serves me right). > > > > > > > > > > DPDK applications may also define _XOPEN_SOURCE for their own > > > > > > needs. They should still be able to use rte_ip.h afterward. > > > > > > > > > > I suppose they can, they would just have (on FreeBSD) to add '-D > > > __BSD_VISIBLE' > > > > > themselves. > > > > > > > > Of course, but public headers should be as self sufficient as possible. > > > > Unless they provide really insane compiler flags, if user applications > > > > get compilation errors after including some header we install on the > > > > system, I think the blame is on DPDK. > > > > > > > > > > I think this reason is > > > > > > enough to go with -D__BSD_VISIBLE under FreeBSD without removing > > > > > > _XOPEN_SOURCE, as it should work regardless. > > > > > > > > > > So do you suggest to add '-D __BSD_VISIBLE' into mlx/failsafe PMDs > > > > > Makefiles/meson.build, or ... ? > > > > > > > > Since headers of our public API potentially require it, it must be > > > > defined globally (unlike _XOPEN_SOURCE which is only local to a few > > > PMDs): > > > > app/meson.build, lib/meson.build, mk/target/generic/rte.vars.mk, > > > > alongside -D_GNU_SOURCE. > > > > > > > > Add it to mlx*/failsafe only if that's not enough. Just make sure > > > > applications inherit this flag. > > > > > > Ok, to summarize, eyour suggestion is: > > > 1. remove -D_XOPEN_SOURCE=... from mlx and failsafe PMDs. > > > 2. add '-D __BSD_VISIBLE' into top level make/meson files > > > (app/meson.build, lib/meson.build, mk/target/generic/rte.vars.mk) Similar > > > to what we doing for -DGNU_SOURCE. > > > > > > If I understand you correctly, then it sounds ok to me. > > > > > > > > > > > > > Looking at the patch [1], I also think there's another, simpler > > > > > > approach: > > > > > > unless really performance critical, defining > > > > > > rte_ipv6_get_next_ext() in rte_net.c instead of a static inline in > > > rte_ip.h should address this issue. > > > > > > > > > > It is performance critical, and I think that function call for each > > > > > ext header is a way too expensive approach. > > > > > Will prefer to keep that function inline. > > > > > > > > OK, a bit cumbersome but since we're heading this way [2], how about > > > > defining our own instead of all the above? > > > > > > > > #define RTE_IPPROTO_HOPOPTS 0 > > > > #define RTE_IPPROTO_ROUTING 43 > > > > ... > > > > > > > > Which could prove handy later as it appears Linux and FreeBSD don't > > > > have the same set of available IPPROTO_* definitions. > > > > > > > > Thoughts? > > > > > > > > [2] "[RFC v2 00/14] prefix network structures" > > > > https://mails.dpdk.org/archives/dev/2019-April/129752.html > > > > > > Yep, that's definitely an option too. > > > But if we going to replace all current references of IPPROTO_ inside DPDK > > > to > > > RTE_IPROTO_ - the change will be massive. > > > And for sure it is out of scope of this patch series. > > > That's probably need to be done after Olivier RFC will be in and should be > > > subject of a separate patch series. > > > Konstantin > > > > I agree that we need RTE_IPPROTO* macros but as Konstantin pointed out this > > would be a huge change and we should do that on top of Oliver's work in > > a separate patch set. > > > > I will propose a patch set with: > > 1. Removed XOPEN_SOURCE macros as they are not needed anymore > > 2. Added BSD_VISIBLE at the top of build system. > > Actually I still suggest to leave the existing _XOPEN_SOURCE for users of > -std=whatever, even if covered globally by _GNU_SOURCE and __BSD_VISIBLE. > I think it's useful as a reminder that they did their homework since this is > macro is itself standard. >
If you insist, I don't mind to keep it - less changes for us, again I am not a maintainer, nor a user of these PMDs. Just don't to see much rationale behind it. Ss I understand from your previous letters - with global flags in place, it would build with -std=... regardless do we have or not XOPEN_SOURCE=... in these PMDs or not. Konstantin > Regarding RTE_IPPROTO*, my suggestion wasn't to convert DPDK entirely, only > to add the missing ones so far only needed by this patch. Given their values > are defined by RFCs, they should be fully compatible and interchangeable > with system definitions. > > I'm fine with either approach in any case. > > -- > Adrien Mazarguil > 6WIND
