Sorry for the late response, increasing the msg_t structure will be great, however this will require changing a lot of binding.
Sorry for disappearing, baby and full time job is a lot :-), hopefully I'm back... On Mon, Aug 29, 2016 at 6:46 PM, Luca Boccassi <[email protected]> wrote: > Sorry, I meant if we go with (1), not (2), we might bump the size as > well, since we are already doing another ABI-breaking change. > > I agree on the solution as well. > > On Mon, 2016-08-29 at 17:12 +0200, Pieter Hintjens wrote: >> I'm confused between the (1) and (2) choices, and can't see where >> bumping the message size fits. >> >> Nonetheless, I think bumping the size, fixing the alignment issues, >> and bumping the ABI version is the best solution here. >> >> On Fri, Aug 26, 2016 at 12:33 PM, Luca Boccassi <[email protected]> >> wrote: >> > I've given some more thoughts and testing to the alignment issue. I can >> > reproduce the problem by enabling alignment checks on x86 too. >> > >> > But most importantly, I think we cannot get away from bumping the ABI >> > with this fix, however we rearrange it, simply because applications need >> > to be rebuilt against the new header to be fixed. A simple rebuild of >> > the libzmq.so is not enough. And the way to do this is to bump the ABI >> > so that distros can schedule transitions and rebuilds and so on. >> > >> > So the choice list is now restricted to: >> > >> > 1) Bump ABI >> > 2) Revert the fix and leave everything broken on sparc64 and some >> > aarch64 (rpi3 seems not to be affected, must depend on the SoC flavour) >> > >> > If we go with 2, we might as well get 2 birds with one stone and bump >> > the zmq_msg_t size to 128 as we have talked about in the past. >> > >> > Doron, this would help with the new UDP based socket types right? >> > >> > Pros of bumping msg size: >> > >> > - we can get rid of the malloc() in the lmsg type case as all the data >> > will fit >> > >> > Cons: >> > >> > - for the vsm/cmsg type cases (for most architectures anyway) it won't >> > fit anymore into a single cacheline >> > >> > Given all this, I'd say we should go for it. >> > >> > Opinions? >> > >> > On Sat, 2016-08-13 at 16:59 +0100, Luca Boccassi wrote: >> >> Hello, >> >> >> >> Trying to give some thoughts again on the libzmq 4.2 release. It's >> >> really long overdue! >> >> >> >> The main issue from my point of view is this change: >> >> >> >> https://github.com/zeromq/libzmq/commit/d9fb1d36ff2008966af538f722a1f4ab158dbf64 >> >> >> >> -typedef struct zmq_msg_t {unsigned char _ [64];} zmq_msg_t; >> >> +/* union here ensures correct alignment on architectures that require >> >> it, e.g. >> >> + * SPARC >> >> + */ >> >> +typedef union zmq_msg_t {unsigned char _ [64]; void *p; } zmq_msg_t; >> >> >> >> >> >> This is flagged by the common ABI checkers tools as an ABI breakage >> >> (see: http://abi-laboratory.pro/tracker/timeline/zeromq/ ). And it makes >> >> sense from this point of view: if some applications on some >> >> architectures are broken due to wrong alignment, they would need to be >> >> rebuilt, and the way to ensure that is to bump the ABI "current" digit >> >> to make sure maintainers do a rebuild. >> >> >> >> On the other hand, signaling an ABI breakage is a pain, and a cause of >> >> major churn for packagers and maintainers. It means for example a new >> >> package has to be created (eg: libzmq5 -> libzmq6), and a transition has >> >> to be started and all reverse dependencies need to be rebuilt. And if >> >> this is pointless for all save a few corner cases (eg SPARC64 as for >> >> above) it's all quite frustrating. >> >> >> >> So we have a choice to make before we release 4.2, four possibilities as >> >> far as I can see: >> >> >> >> 1) Ignore the ABI checkers and get yelled at by maintainers and >> >> packagers. Also the SPARC64 users will most likely NOT get their bug >> >> fixed >> >> 2) Bump ABI revision to 6 and get yelled at by maintainers and packagers >> >> 3) Revert the above change and postpone it to when we have a more >> >> generally useful reason to break ABI (bump zmq_msg_t from 64 to 128 >> >> bytes for example, Doron?) >> >> 4) Try to be clever and revert the above change and use something like >> >> #pragma pack(8). This will fool the ABI checkers (I tried it), and given >> >> that typedef is only used externally to allocate the right size it >> >> shouldn't actually affect anything, apart from the users of SPARC64 >> >> which should get the bugfix with this too. This is very sneaky :-) >> >> >> >> CC'ing Lazslo, the Debian maintainer, given what we choose to do might >> >> result in a lot of work for him :-) >> >> >> >> Opinions? >> >> >> >> Kind regards, >> >> Luca Boccassi >> >> >> >> On Tue, 2016-05-03 at 10:39 +0200, Pieter Hintjens wrote: >> >> > Hi all, >> >> > >> >> > I'm just throwing some ideas on the table. We have a good package of >> >> > work on master and it's probably time to make a 4.2 release. >> >> > >> >> > Luca has already back-ported the enable/disable draft design from >> >> > zproject (CZMQ et al). Yay! So we can now release stable master >> >> > safely, while continuing to refine and extend the draft API sections. >> >> > >> >> > I propose: >> >> > >> >> > - to end with the stable fork policy; this was needed years ago when >> >> > we had massively unstable masters. It's no longer a problem. >> >> > - to use the github release function for libzmq releases and deprecate >> >> > the separate delivery of tarballs. >> >> > - we aim to make a 4.2.0 rc asap, then fix any issues we get, with >> >> > patch releases as usual. >> >> > - we backport the release function to older maintained releases (4.1, >> >> > 3.2) so that their tarballs are provided by github instead of >> >> > downloads.zeromq.org. >> >> > >> >> > Problems: >> >> > >> >> > - this will break a few things that depend on downloads.zeromq.org. To >> >> > be fixed as we go. >> >> > - github tarballs are not identical to source tarballs, particularly >> >> > they lack `configure`. I propose changing our autotools build >> >> > instructions so they always start with `./autogen,sh` no matter where >> >> > the sources come from. >> >> > >> >> > I think this will work and also let us gracefully deprecate/switch off >> >> > the downloads box. >> >> > >> >> > -Pieter >> >> > _______________________________________________ >> >> > zeromq-dev mailing list >> >> > [email protected] >> >> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev >> >> >> >> >> > >> > >> > >> > _______________________________________________ >> > zeromq-dev mailing list >> > [email protected] >> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev >> _______________________________________________ >> zeromq-dev mailing list >> [email protected] >> http://lists.zeromq.org/mailman/listinfo/zeromq-dev > > _______________________________________________ zeromq-dev mailing list [email protected] http://lists.zeromq.org/mailman/listinfo/zeromq-dev
