Irc discussions from #mirage on 29-03-2017

Written by lobo
Classified under: irclog
Published: 2017-06-25 (last updated: 2017-06-25)

29-03-2017 15:01 yomimono hi folks!

29-03-2017 15:01 mato hey ho

29-03-2017 15:01 thomasga \o/

29-03-2017 15:01 yomimono it having been two weeks (give or take a couple hours) since our last biweekly (fortnightly) catchup, we should probably have another one

29-03-2017 15:01 reynir o/

29-03-2017 15:01 lobo hi

29-03-2017 15:02 amirmc .

29-03-2017 15:02 yomimono as usual the agenda is at

29-03-2017 15:02 yomimono it's rather short this week but the first item will probably get a lot of discussion :)

29-03-2017 15:03 yomimono said item: Build system RFC (see mirage/mirage#818 and the email thread)

29-03-2017 15:04 hannes what is the purpose of that agenda item? collecting random comments + opinions about jbuilder here? or anything in particular?

29-03-2017 15:05 yomimono I was just looking at the page history wondering who should be talking now ;)

29-03-2017 15:05 yomimono so it looks like amirmc added this agenda item a while ago, is he here?

29-03-2017 15:05 yomimono oh, you've just said ., you definitely are

29-03-2017 15:05 reynir Yes, <5 minutes ago

29-03-2017 15:05 amirmc I added after avsm mentioned on the email list. I figured it might be worth talking about now., so it was meant as a reminder.

29-03-2017 15:06 amirmc If there are no comments, or things to chat about synchronously, then we can keep it on the issue.

29-03-2017 15:06 yomimono well, my question about this is whether anyone has taken the time to follow hannes and talex5's advice on how to proceed with evaluating jbuilder

29-03-2017 15:06 demonimin I use ppx.lwt currently, hopefully that will get ported

29-03-2017 15:07 yomimono namely "lease try some difficult packages first -- i.e. those which need C libraries to be compiled for multiple targets"

29-03-2017 15:08 mato I agree with hannes' assessment.

29-03-2017 15:08 hannes other issues include: how to execute (depopt) tests? how to build docs? how to release packages with jbuilder (is sth like topkg lint fulfilled by construction?)?

29-03-2017 15:08 thomasga I have been trying jbuilder a bit and it is very fast

29-03-2017 15:09 Drup Contributions to lwt are welcome.

29-03-2017 15:09 thomasga but I really don't want to regress on the publishing workflow that we have with topkg

29-03-2017 15:09 hannes and - keeping moving parts low - maybe someone should finish the topkg ports first? maybe someone can come up with a topkg which calls out to jbuilder instead of ocamlbuild (it seems avsm doesn't think this is a good idea)

29-03-2017 15:09 mato hannes: +1

29-03-2017 15:10 yomimono yes, I would really hate to lose the workflow automation of topkg

29-03-2017 15:10 thomasga for me that's the only blocker, until then I am pretty happy to continue experimenting

29-03-2017 15:10 yomimono I don't think it's sensible to take an approach that regresses there

29-03-2017 15:10 hannes don't get me wrong -- I'd really love to get rid of ocamlbuild, and jbuilder looks promising

29-03-2017 15:10 rgrinberg sounds like we should wait until topkg + jbuilder is ready then. Although I don't know how that would look like

29-03-2017 15:10 rgrinberg Did daniel say something about supporting jbuilder in topkg?

29-03-2017 15:11 Drup he will not do it himself

29-03-2017 15:11 thomasga yes, he said he was happy to relicense some bits of code if it helps

29-03-2017 15:11 rgrinberg hannes: the question about depopts is easy in your situation. You should get rid of them and have proper sub packages.

29-03-2017 15:11 yomimono, "I think it would be much more productive that jbuilder provides a topkg-like release workflow by itself"

29-03-2017 15:11 thomasga and that someone should copy/paste the bits of code needed inside jbuilder

29-03-2017 15:11 demonimin as I understand it, daniel wanted jbuilder to present the same api as topkg for use in opam

29-03-2017 15:13 thomasga topkg works by calling the build system with a list of targets

29-03-2017 15:13 thomasga which are the one the package wants to install

29-03-2017 15:13 thomasga I guess jbuilder build <the list of targets> should work

29-03-2017 15:13 hannes rgrinberg: let me rephrase this, you mean the solution is to always have a 1:1 correspondence of opam and ocamlfind packages? and never have some package?

29-03-2017 15:13 thomasga and yes, I tend to agree about removing depopts

29-03-2017 15:14 thomasga (when possible)

29-03-2017 15:14 rgrinberg never is a strong word. but a strong preference against depopts is what we'd wnt

29-03-2017 15:14 thomasga a "a 1:1 correspondence of opam and ocamlfind packages" seems like a good idea too

29-03-2017 15:14 thomasga (e.g. less names)

29-03-2017 15:15 hannes then I'd expect someone to clean up e.g. tcpip using jbuilder as a PoC... and maybe also enlighten people on how to relese multiple packages out of a single repository at once..

29-03-2017 15:16 thomasga @hannes: for the multi-pacakges per repo, see

29-03-2017 15:16 hannes (I agree that a 1:1 opam to ocamlfind is a good idea)

29-03-2017 15:16 hannes thomasga: no jbuilder in there afaics

29-03-2017 15:18 thomasga ha ok. So let me rephrase my position: until we have the same workflow as we have today with topkg, I think it is very unwise to switch the mirage packages to jbuilder.

29-03-2017 15:18 thomasga I think we all agree here

29-03-2017 15:18 thomasga (e.g. Mirage3 without topkg would have been a nightmare to manage)

29-03-2017 15:19 rgrinberg that's b/c ya'll have 50 repos ;)

29-03-2017 15:19 thomasga :-)

29-03-2017 15:19 rgrinberg thomasga: are you convinced by daniel's assesment that jbuilder should reimplement the parts of topkg that it is missing?

29-03-2017 15:19 hannes thomasga: well... this raises two questions: what are the mirage packages? are these PRs on various repos about jbuilder getting merged?

29-03-2017 15:20 thomasga @hannes: as far as I know only the _oasis repos are getting relifted with jbuildee

29-03-2017 15:20 thomasga I'd say: oasis < jbuilder < topkg

29-03-2017 15:20 thomasga (today)

29-03-2017 15:20 rgrinberg hannes: some packages have never been topkg'd in the first place. Also for packages that strongly rely on depopts today, I believe that splitting them into proper opam sub packages is more important than a smooth release process.

29-03-2017 15:21 thomasga rgrinberg: I am not sure how to merge topkg and jbuilder features, but I would trust Daniel on this one

29-03-2017 15:21 thomasga I think he said someone should just "vendor" topkg inside jbuilder

29-03-2017 15:22 hannes rgrinberg: counterarguments include

29-03-2017 15:22 talex5 I think the problem is that there is quite a lot of overlap between topkg (which creates an opam .install file) and jbuilder (which does too, as I understand it).

29-03-2017 15:22 rgrinberg hannes: those don't have depopts

29-03-2017 15:22 rgrinberg so the gain from jbuilder is marginal

29-03-2017 15:23 Drup I think packages such as lwt are a better targets

29-03-2017 15:23 thomasga agreed

29-03-2017 15:23 talex5 So topkg+jbuilder would result in duplication of some metadata.

29-03-2017 15:23 hannes rgrinberg: yes, they're (against your statement earlier) moving some topkg'ed package to jbuilder...

29-03-2017 15:23 thomasga talex5: clearly need to sort that kind of overlap too

29-03-2017 15:23 Drup big, multiple sub packages, C bindings, ppx and camlp4, currently uses oasis

29-03-2017 15:24 rgrinberg talex5: the overlap is as follows AFAIK: generation of .merlin, pkg.install, and META files. All of those things should clearly be done by jbuilder though

29-03-2017 15:24 Drup If someone (aka rgrinberg) can converts that and make a guide, lot's of packages can be converted

29-03-2017 15:24 rgrinberg hannes: i might have misspoke, I think transitioning to jbuilder from topkg only makes sense if your package suffers from depopts

29-03-2017 15:25 thomasga btw, I have a repo with multiple packages, C bindings, tests and jbuilder work great

29-03-2017 15:25 Drup (and it'll polish about the initial rough edges to make everything fit)

29-03-2017 15:25 talex5 Yes, so the ideal system would be jbuilder + something for handling releases (possibly based on topkg's release system).

29-03-2017 15:25 Drup -about

29-03-2017 15:25 thomasga but I will need to publish some packages at one point :p

29-03-2017 15:25 hannes thomasga: including multiple targets/crosscompilation for the C artifacts?

29-03-2017 15:25 yomimono good point about lwt, Drup, wihch I don't want to see get lost

29-03-2017 15:26 thomasga hannes: not yet

29-03-2017 15:26 thomasga also topkg has a nice watermarking system, doc generation, etc

29-03-2017 15:26 hannes (I'm really easy, please port to jbuilder -- I just won't do any of it (did sufficent oasis -> topkg work), and expect the same featureset as before)

29-03-2017 15:26 thomasga lots of coold stuff

29-03-2017 15:26 Drup (I'm personally a lot more favorable to jbuilder's project descriptions that to topkg's lack of it)

29-03-2017 15:27 Drup (so when edges get a bit rounder, I might port ocsigen stuff to it)

29-03-2017 15:27 thomasga if someone can just do a mix of both system (e.g. fast builds + nice release workflow) that would just be great

29-03-2017 15:28 rgrinberg Drup: yeah, that's pretty clear. This is where I see the friction between topkg and jbuilder though. topkg shouldn't need its project description DSL when used with jbuilder

29-03-2017 15:30 rgrinberg thinking out loud: a jbuilder flavor jbuilder will simply construct its project description data structure from the jbuild sexps. or use jbuilder's api.

29-03-2017 15:32 yomimono an attempt to summarize: most people would be fine with switching to jbuilder if it didn't regress on the publishing workflow provided by topkg

29-03-2017 15:32 yomimono it would be some work to do and that work would be helped by a nice complicated example port like lwt

29-03-2017 15:32 yomimono with a nice writeup

29-03-2017 15:33 yomimono I don't expect any movement on this without some work to provide jbuilder with the functionality we're missing and some work to provide the example mentioned above

29-03-2017 15:33 yomimono further comments or explanations of my misunderstanding welcome

29-03-2017 15:33 hannes another feature missing in jbuilder seems to be mli-only modules...

29-03-2017 15:34 rgrinberg porting lwt to jbuilder just to for an example is pretty cruel :P. it's likely a massive task. But I think a typcial project with cstubs/ppx is in order.

29-03-2017 15:34 thomasga need to run sorry, but I fully agree with the summary!

29-03-2017 15:34 hannes it's not all about release workflow, also actual missing features... the cross-compilation of C code, atm usin ocl-stubblr etc., would be another feature we need for some libraries

29-03-2017 15:34 Drup rgrinberg: well, most people who learned oasis learned it by looking at lwt's oasis (written by diml!), why not repeat history ? :D

29-03-2017 15:35 yomimono thanks hannes, that's a good point

29-03-2017 15:36 hannes but it is obviously not a all-or-nothing thing: different packages can use different build systems (and luckily those with c bindings are rather rare in the mirage ecosystem)

29-03-2017 15:36 rgrinberg hannes: is that essential? just rename your .mli to .ml :P Agreed on the other points though.

29-03-2017 15:36 rgrinberg Yeah, if topkg was a decent wrapper around both systems, you could argue that the transition could be done gradually

29-03-2017 15:37 hannes rgrinberg: yes, tis is essential. no, renaming is not an option.

29-03-2017 15:37 rgrinberg is symlinking an option? :)

29-03-2017 15:37 yomimono No.

29-03-2017 15:37 hannes no. doesn't work on windows.

29-03-2017 15:38 hannes and mli files are distributed/installed, whereas ml are not. if you duplicate the files (copy), each change will have to be done twice

29-03-2017 15:38 rgrinberg ok then a manual rule that copies .mli -> .ml is probably doable. hannes if you think it's essential you should leave a comment here:

29-03-2017 15:38 rgrinberg I couldn't come up with any arguments why I couldn't do without it

29-03-2017 15:39 hannes a copy rule at build time may be an ok solution.. i will not distract myself into another build system

29-03-2017 15:40 mato rgrinberg: Random question (since I literally just ran into this), is the jbuilder dependency on bash absolutely necessary?

29-03-2017 15:40 rgrinberg there's no hard dependency on bash. just make sure not to use bash in your jbuilder rules

29-03-2017 15:41 hannes (mato: I use an old opam-repo snapshot atm without any newish sexplib etc. to avoid any of the struggle)

29-03-2017 15:41 mato right, so it's the downstream's (in this case ppx_ast's) fault?

29-03-2017 15:42 rgrinberg

29-03-2017 15:42 rgrinberg that seems suspcious

29-03-2017 15:42 hannes AFAICS jbuilder explicitly calls out to bash. unclear why.

29-03-2017 15:43 mato hannes:

29-03-2017 15:43 yomimono unless there are further points that could be helped by synchronous discussion, I'd like to propose that we move on

29-03-2017 15:45 yomimono hearing no objections: next item is meetbot, which I said last time I'd try to take a look at by this meeting

29-03-2017 15:45 yomimono do or do not, there is no try, and in this case I did not

29-03-2017 15:45 rgrinberg okay!

29-03-2017 15:46 yomimono if we have other volunteers to look into that, I would be happy to see someone else take the time and set it up

29-03-2017 15:46 yomimono otherwise I'll try to find time before our next meeting in April

29-03-2017 15:46 yomimono other items?

29-03-2017 15:46 mato um

29-03-2017 15:47 amirmc I can add an AOB item about blog posts for the website about the hackathon.

29-03-2017 15:47 yomimono please do

29-03-2017 15:47 mato well, as of about an hour ago,I have all the standalone ukvm tests passing on FreeBSD/vmmapi

29-03-2017 15:47 djwillia nice mato@

29-03-2017 15:48 yomimono that's great!

29-03-2017 15:48 mato I would have had a mirage unikernel tested on FreeBSD by now, were it not for random breakage in the MirageOS dependencies on FreeBSD

29-03-2017 15:48 hannes mato: nice! what about clock?

29-03-2017 15:48 mato hannes: I've solved clock, but can't test it properly w/o Mirage, which I can't install because blah.

29-03-2017 15:48 djwillia the high level story for Solo5/ukvm is there are a bunch of in-progress ports that are hopefully going to merge together into a big happy family soon

29-03-2017 15:49 djwillia originally we had the virtio and ukvm backends for Solo5 (both x86)

29-03-2017 15:49 hannes amirmc: to address your topic: gemma mentioned she has collected posts, and there'll be sth likely this week... avsm likely knows more

29-03-2017 15:49 gemmag amirmc: I've collected the 10 trip reports we have received so far as well as some photos - I'm expecting a few more, then passing over to avsm

29-03-2017 15:50 djwillia ukvm only ran on Linux/KVM on an x86

29-03-2017 15:51 djwillia now some collaborators from ARM have got it running on Linux/KVM on ARM

29-03-2017 15:51 amirmc hannes gemmag: great!

29-03-2017 15:51 avsm i can do a consolidated edit of the blogpost and send a PR to mirage-www

29-03-2017 15:51 avsm djwillia: have they actually booted on arm64 now? thats awesome!

29-03-2017 15:51 djwillia and mato has got it running on FreeBSD/vmmapi.h, and I have got it working on MacOSX/Hyperisor.framework

29-03-2017 15:52 djwillia the thing that makes all this difficult is that there are multiple "platforms" as well as multiple "architectures"

29-03-2017 15:52 djwillia mato has a plan to make them all live happily together, which he is testing out with the FreeBSD port

29-03-2017 15:53 djwillia avsm: i'm not sure if it's arm64 or arm32, mato do you know?

29-03-2017 15:54 djwillia the cool thing about this is that on all of these platform/arch combos we should be able to run the tiny "unikernel monitor" (ukvm) instead of needing a more general-purpose VMM like QEMU

29-03-2017 15:54 mato djwillia: avsm: arm64

29-03-2017 15:54 djwillia awesome!

29-03-2017 15:56 yomimono thanks for the updates mato and djwillia :)

29-03-2017 15:56 mato yeah, i think things are coming together rather nicely, hopefully april will be the month where Solo5 (and thus Mirage) gains a bunch of new targets

29-03-2017 15:58 yomimono :D that's a great note on which to conclude I think!

29-03-2017 15:58 yomimono thanks, everyone!

29-03-2017 15:59 mato thanks yomimono for coordinating

29-03-2017 15:59 djwillia thanks!

29-03-2017 16:02 avsm thanks!