19:36 <aweinstock> I'm trying to follow along with the mirage tutorial at https://mirage.io/wiki/hello-world, and can't build tutorial/noop; the error involves 'Error: Unbound module OS' in main.ml

19:36 <aweinstock> there's a commit that fixes something with the same symptom in 2016: https://github.com/mirage/mirage/issues/511

19:38 <aweinstock> I have ocaml 4.02.3 installed through debian stretch repo, opam 1.2.2 via 0install, and mirage 2.6.1 via opam

19:38 <aweinstock> any suggestions for what to try next?

19:41 <hannes> aweinstock: you should upgrade your OCaml and then get a newer mirage. 3.x is the current major release :)

19:42 <hannes> aweinstock: since you have opam, you can use `opam switch 4.04.2` to get a new OCaml :)

19:42 <hannes> (or opam switch 4.05.0 if you feel adventourus)

19:42 <aweinstock> "Now compiling OCaml. This may take a while, please bear with us..."

19:42 <hannes> mirage 3.x dropped 4.02 compatibility, the minimum version needed is 4.03 now.

19:43 <aweinstock> (`opam switch` is nice to know about)

19:43 <hannes> it will compile and install into ~/.opam/4.04.2/ -- where it also installs all the packages

19:43 <aweinstock> once I have the new ocaml, opam will automatically get a newer mirage?

19:45 <hannes> no. once OCaml is installed, you need to adjust environment variables in your shell -- by running "eval `opam config env`"

19:45 <hannes> when this is done, "opam install mirage" will get you a new mirage :)

19:54 <aweinstock> noop builds now (main.native runs with no errors)

19:58 <hannes> \o/

19:58 <aweinstock> hello builds too (same directory)

19:58 <aweinstock> s/directory/repo/

19:58 <hannes> depending on your environment, you may want to try mirage configure -t ukvm ;)

19:59 <hannes> to get an actually freestanding unikernel (using kvm)

19:59 <aweinstock> ukvm works with qemu?

19:59 <hannes> it works with kvm from the linux kernel

20:00 <aweinstock> (also, do I need to `make depend` after each `mirage configure -t foo`?)

20:00 <hannes> it does - in contrast to other kvm linux vms - NOT use qemu

20:00 <hannes> yes, make depend installs dependency - and they vary between targets

20:00 <hannes> but of course you can just run make and see whether it fails or not (and if it fails, run make depend)

20:01 <aweinstock> `./ukvm-bin hello.kvm` works (`./hello.kvm` on it's own segfaults)

20:02 <hannes> yes! well, hello.kvm is a ELF binary expecting to be run in kernel context, thus running it as a unix process won't work

20:02 <aweinstock> is it possible to run the .kvm file under qemu?

20:03 <hannes> I guess the virtio stuff can be run under qemu, but the kvm unlikely... not sure... you may want to ask that on the mailing list where more people are active :)

20:25 <aweinstock> qemu-system-x86_64 -serial stdio -display none -kernel hello.virtio # this seems to work

20:27 <hannes> ! :)