On Mon, Feb 05, 2018 at 03:59:18PM +0100, Adrien Mazarguil wrote: > On Mon, Feb 05, 2018 at 12:37:34PM -0200, Marcelo Ricardo Leitner wrote: > > On Mon, Feb 05, 2018 at 03:16:21PM +0100, Thomas Monjalon wrote: > > > 05/02/2018 14:44, Adrien Mazarguil: > > > > On Mon, Feb 05, 2018 at 10:58:06AM -0200, Marcelo Ricardo Leitner wrote: > > > > > On Mon, Feb 05, 2018 at 12:24:23PM +0000, Van Haaren, Harry wrote: > > > > > > > From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Marcelo > > > > > > > Ricardo Leitner > > > > > > > Sent: Monday, February 5, 2018 12:14 PM > > > > > > > To: Adrien Mazarguil <adrien.mazarg...@6wind.com> > > > > > > > Cc: Thomas Monjalon <tho...@monjalon.net>; dev@dpdk.org; Shahaf > > > > > > > Shuler > > > > > > > <shah...@mellanox.com>; Nelio Laranjeiro > > > > > > > <nelio.laranje...@6wind.com> > > > > > > > Subject: Re: [dpdk-dev] [PATCH v2 3/4] net/mlx: version rdma-core > > > > > > > glue > > > > > > > libraries > > > > > > > > > > > > > > On Mon, Feb 05, 2018 at 12:24:02PM +0100, Adrien Mazarguil wrote: > > > > > > > > On Sun, Feb 04, 2018 at 03:29:38PM +0100, Thomas Monjalon wrote: > > > > > > > > > 02/02/2018 17:46, Adrien Mazarguil: > > > > > > > > > > --- a/drivers/net/mlx4/Makefile > > > > > > > > > > +++ b/drivers/net/mlx4/Makefile > > > > > > > > > > @@ -33,7 +33,9 @@ include $(RTE_SDK)/mk/rte.vars.mk > > > > > > > > > > > > > > > > > > > > # Library name. > > > > > > > > > > LIB = librte_pmd_mlx4.a > > > > > > > > > > -LIB_GLUE = librte_pmd_mlx4_glue.so > > > > > > > > > > +LIB_GLUE = $(LIB_GLUE_BASE).$(LIB_GLUE_VERSION) > > > > > > > > > > +LIB_GLUE_BASE = librte_pmd_mlx4_glue.so > > > > > > > > > > +LIB_GLUE_VERSION = 18.02.1 > > > > > > > > > > > > > > > > > > You should use the version number of the release, i.e. 18.02.0 > > > > > > > > > Ideally, you should retrieve it from rte_version.h. > > > > > > > > > > > > > > > > Keep in mind this only needs to be updated when the glue API > > > > > > > > gets > > > > > > > modified, > > > > > > > > and this "18.02.1" string may remain unmodified for subsequent > > > > > > > > DPDK > > > > > > > > releases, probably as long as the PMD doesn't use any new > > > > > > > > rdma-core calls. > > > > > > > > > > > > > > > > We've already backported this patch to 17.02 and 17.11, both > > > > > > > > requiring > > > > > > > > different sets of Verbs calls and thus a different version, > > > > > > > > hence the > > > > > > > added > > > > > > > > "18.02" as a starting point. The last digit may have to be > > > > > > > > modified > > > > > > > possibly > > > > > > > > several times between official DPDK releases while work is > > > > > > > > being done on > > > > > > > the > > > > > > > > PMD (i.e. per commit). > > > > > > > > > > > > > > > > In short it's not meant to follow DPDK's public versioning > > > > > > > > scheme. If you > > > > > > > > really think it should, doing so will make things more complex > > > > > > > > in the > > > > > > > > Makefile, which will have to parse rte_version.h. What's your > > > > > > > > opinion? > > > > > > > > > > > > > > What about appending date +%s output to it? It would be stricter > > > > > > > and > > > > > > > automated. > > > > > > > > > > > > Adding current timestamp or date into a build breaks > > > > > > reproducibility of builds, so is > > > > > > generally not recommended. > > > > > > > > > > Then the sha1sum of mlx4_glue.h. > > > > > With this the size check I mentioned on the other patch would become > > > > > redundant and unnecessary. > > > > > > > > Using a strong hash algorithm to version a library/symbol, while > > > > possible, > > > > seems a bit overkill and results in ugliness: > > > > > > > > librte_pmd_mlx4.so.c4ca4eaf2fe975ead83453458f4f56db49e724f3 > > > > Ugh yes, but it wouldn't need to be that visible. A pointer on > > mlx*_glue and a define on PMD would be enough already. As in, an > > extended check to the versioning. > > I thought you suggested this as a replacement. I'm not sure we need or want > to go this far. The current string comparison is really not worse than > standard symbol versioning, which doesn't check symbol properties besides > whether they are functions or other objects. We could have used C++ with > automatically mangled symbol names for that, however that again would make > things way more complex than necessary. > > > > > Using a weak one like CRC32 for a shorter name poses a risk of > > > > collision. Moreover the next time someone decides to update all version > > > > notices or modify a comment will impact that hash. We'd need to isolate > > > > the > > > > symbol definition itself, ignore parameter names in function prototypes > > > > and > > > > only then we may get a somewhat meaningful hash describing a given ABI. > > > > That's what I meant with stricter. Yes it would catch such > > situations, but you tell me on how much we want to protect/restrict > > here. Do you see a reason for building only the dpdk/pmd side and not > > the glue library at a time? > > No, they're always built together. We're only adding this versioning to > avoid issues when users somehow end up with several DPDK versions installed > on their system, or with leftovers of previous releases lying around. That's > all we need to solve here. dlopen()'ing the proper file takes care of that, > the symbol version number check afterward is performed just in case.
Interesting. These leftovers probably wouldn't be there if it wasn't versioned in the first place. :-) > > > > > Given the added complexity, is there really a problem with simple > > > > version > > > > numbers we increment every time something gets modified? (Note this is > > > > already how our .map files work, they're not generated automatically) > > > > > > Our map files show the major version where a symbol was introduced. > > > It is simple because no symbol can be introduced in a minor version. > > > > > > > How about keeping things as is? > > > > I don't really see the need of unique filenames. The next patch is > > already leveraging RTE_EAL_PMD_PATH, which if versioned should be > > enough for this, no? > > As you said, "if" versioned. As an undocumented empty string by default, > there's no way to be sure. Leaving the PMD version its internal but > (unfortunately) exposed bits will certainly prevent mistakes. > > > > You are using 18.02.1 while it is introduced in 18.02.0. > > > If you don't want to correlate the .so version number with DPDK version > > > number, maybe that 1, 2, 3 would be a simpler choice (less confusing). > > > > +1 > > Then are you fine with the "18.02.0" suffix? Not really, sorry. It was more for the "1, 2, 3" sequence or tying it to dpdk version. With the latest replies, I don't think the reasoning is enough to justify these extra checks, but I won't oppose to including it. Marcelo