Re: MirageOS meeting 2024-04-08

[Hannes Mehnert <hannes@xxxxxxxxxxx>]

Hello,

our next meeting is on April 29th 09:00 CEST 
(https://www.timeanddate.com/worldclock/fixedtime.html?msg=MirageOS+call&iso=20240429T09&ah=1) 
on https://meet.jit.si/mirageos-call
Agenda is tracked on https://pad.data.coop/wGS4r8RyTKqQ73mcw7FrwA?both#


The meetings notes from today:

Participants: Magnus, Pierre, Kaushik, Vincent, Shakthi, Reynir, Hannes, 
Thomas, Samuel
- Why are you here?
   - Kaushik: 2nd meeting, want to understand what he didn't know that 
he didn't know; use MirageOS in real-world problem solving
   - Vincent: working at Tarides on SpaceOS, still learning MirageOS, 
learn and understand what is going on; prepare the Marrakech retreat
   - Pierre: associate professor in network security, know and 
understand what people are working on in the MirageOS ecosystem, uses 
QubesOS (and the mirage-qubes-firewall) and MirageOS, is motivated to 
get rid of cstruct (based on bigarrays, there are issues (with q-m-f & 
bigarray due to malloc)), interested in the OCaml 5 release of MirageOS 
for better performance
   - Magnus: working on MirageOS since ~10 years, interested in the 
technology, worked on MirageOS in Docker, Tarides, now back to research 
-- working e.g. on IncludeOS/MirageOS performance with Alfred
   - Shakthi: works at Tarides on the ocaml.org team, fixing CI issues, 
looking at good first issues for newcomers
   - Samuel: engineer at Tarides, worked in the last months on OCaml 5 
support for MirageOS (now solo5 works on OCaml 5.2 beta), works on 
Unikraft support for MirageOS, has interest in low-level stuff
   - Reynir: work in robur.coop with hannes and dinosaure, we develop 
MirageOS applications and maintain quite some libraries, interest to 
develop and deploy applications
   - Thomas: working on MirageOS for a while, happy to see the call 
starting again, still there are several parties interested in MirageOS, 
nice area of system research, interest: how to apply that to deployment 
- how to improve the IT landscape, MirageOS brings something new to IT 
(type-safe, memory-safe, formal verification): low-level systems with 
high-level languages, short term interest: CLI tool is more usable / 
friendly -- the OCaml ecosystem has evolved a lot since MirageOS started 
-- take ideas from MirageOS and upstream them to OCaml
   - Hannes: Interest in getting MirageOS used & deployed -- has had 
this goal for roughly a decade since he started on Mirage. Have done a 
PhD about formal verification of java programs. Would like to have more 
formally verified systems, so joined Mirage OS project where there is 
less mutable state. Worked on network protocols. Recent months worked on 
performance as we should have good performance when we run without 
kernel & user space. Not afraid of big API changes - they are a 
challenge. Big performance bottleneck is bigarray allocations, so recent 
PRs have been about replacing cstruct with string or bytes with 
promising benchmark results. How do we safely and pragmatically remove 
bounds checks? Worked on dependently typed systems such as Coq (now 
Rocq) and Idris where this is somewhat easier to express safely. Wants 
people to run their own services instead of using Google etc. Interested 
in getting reproducible builds for deployment reasons. Also interested 
in binary sizes. Getting more deployments requires getting more people 
involved => organizing retreats and hanging out on the weekly call to 
get more people interested/involved (since it is not feasible to do it 
alone).
- Proposal for next MirageOS release 4.5.0 (Thomas)
    - Contents: what we have now in `main` (main update: runtime arguments)
    - When: before or after the retreat?
    - Proposal: Dune UX not quite ready for 5.0, better to release 
current version. Would be nice to release this before the retreat, so 
people there have an opportunity to test. So suggest tagging the release 
now and updating the documentation. Then continue discussion about other 
features.
    - Will make release before the retreat
- Next: better Dune integration with Mirage
    - Design doc: 
https://gist.github.com/samoht/98127448fcf6a2483fa36099649fba5a -- 
feedback welcome!
    - PR: https://github.com/mirage/mirage/pull/1495
    - Blockers: bugs in Dune - need experiments with the UX/UI (promotion?)
- Next: OCaml5 + Mirage
    - PR almost ready: 
https://github.com/shym/ocaml-solo5/tree/ocaml-5.2 with its 
[Description](https://paste.sr.ht/~rustyne/0f76561709ca6c28852fae312e835e1059918f6e).
    - Hannes: this is very exciting. Just to be clear, the new 
ocaml-solo5 will only support OCaml 5.2, if we need releases for 4.x 
compatibility, we'll just branch off the latest release and put in changes
    - Thomas: it would also be nice if cross-compilation worked again 
on MacOS, can test
- Next: `dune pkg` + Miragemail-betreuung bis nächsten montag übernehmen
- The performance perspective: "no-cstruct" and bounds checking (Hannes)
  - opam overlay https://github.com/robur-coop/no-cstruct
  - Hannes: would be nice to have a mirage release that would support 
this as it needs changes to the mirage tool
  - Started thread to discuss using type system for bounds checking, 
but looks like this would require ppx right now, which I'd like to 
avoid: 
https://discuss.ocaml.org/t/bounds-checks-for-string-and-bytes-when-retrieving-or-setting-subparts-thereof/14422/6
  - Interested in testing whether programs runs faster if bounds checks 
are removed from the compiler, how much faster is it?
    - `-unsafe` doesn't remove bounds checks from `String.get_*`
    - but a modified Stdlib (or compiler) emitting no bounds checks 
could do the trick
    - then measure on some real applications and take a look at the 
difference
- Random/Clock/Time functors (Hannes) 
https://github.com/mirage/mirage/issues/1513
    - As Hannes understands, a functor is useful if we use a single 
implementation multiple times (e.g. Set/Map -- a set of string, a set of 
int)
    - All Mirage unikernels are functorised over these. Have not seen 
different implementations of these, could we simplify the unikernels to 
not use functors for these?
    - we could replace that by the "linking trick" (dune variants)
    - testing sometimes (such as mirage-tcpip) uses a clock that runs 
faster than - would be great to cope with that
- Next meeting in three weeks (Apr 29th 09:00 CEST), skip one week due 
to retreat -- 
https://www.timeanddate.com/worldclock/fixedtime.html?msg=MirageOS+call&iso=20240429T09&ah=1
On 05/04/2024 17:59, Magnus Skjegstad wrote:
> Hi everyone,
>
> The next MirageOS community call will be Monday April 8th at 9:00-10:00 CEST.
>
> As usual everyone is welcome to attend this bi-weekly meeting. The current 
> agenda is here: https://pad.data.coop/wGS4r8RyTKqQ73mcw7FrwA
>
> Feel free to add any additional items you'd like to discuss.
>
> The Jitsi link for the meeting is https://meet.jit.si/mirageos-call
>
> See you there,
>
> Magnus