13:41 <kakekongen> What's the status regarding ctypes in Mirage (hvt in particular)? I get a buttload of undefined references.

13:43 <kakekongen> It compiles properly with the unix target, but not with the hvt target

13:46 <hannes> kakekongen: AFAIK nobody has really invested the work to get ctypes running with MirageOS. it's not clear to me what the benefit would be in any case, given that there's no libc in a MirageOS unikernel..

13:47 <hannes> this means that all C bindings need to be carefully crafted under the assumption that no symbols are around.. (well, maybe memcmp and memmove)..

13:48 <kakekongen> The issue is my wanting to use the argon2 library for password hashing.

13:48 <kakekongen> In other words, I would be better off using a different library for that purpose? Like something from digestif?

13:51 <hannes> yes, well, or you (a) implement argon2 in ocaml (b) find an argon implementation that doesn't use many external (libc) functions, and interface it manually. intuitively I'd try (b) for 2 hours

13:51 <hannes> (and yes, argon2 would be nice to have mirageos-ready)

15:05 <hannes> kakekongen: there's also https://github.com/abeaumont/ocaml-pbkdf and https://github.com/abeaumont/ocaml-scrypt-kdf/ as alternatives (IIRC they serve the same purpose as argon2)

15:06 <h01ger> hannes: thanks for your mail. will act on it until friday. still typing little (but more than the last 3 weeks...)

15:07 <kakekongen> Ahh, yeah. I am looking at the scrypt-kdf atm. Would be really interesting to make argon2 mirage-ready, but for me that would be a project I would do during weekends, so I think I'll stick to scrypt atm

15:07 <kakekongen> What is required for a library to run under MirageOS hannes?

15:08 <hannes> kakekongen: as mentioned, a pure OCaml version would work out of the box :)

15:08 <kakekongen> For C backends, what would be the requirements for that part?

15:09 <hannes> if you want to interface C code, as you mentioned earlier - there's no ctypes support - which means you've to manually bind the API.

15:09 <kakekongen> Or would that be a hassle?

15:09 <hannes> as i mentioned above, the C functions supported by MirageOS are very limited, take a look at https://github.com/mirage/ocaml-freestanding/tree/master/nolibc what we ship

15:10 <kakekongen> Ahh, that was exactly what I was looking for, thanks! :)

15:11 <hannes> if libargon2.so does only use these functions, it should work out of the box. if they use more libc functions, you'll have to either integrate them into the binding (or ocaml-freestanding -- but i'm pretty against including more C functions there ;) (though i may be convinced))

15:11 <kakekongen> Nice to know ;)

15:12 <hannes> it's morally "whatever OCaml runtime really needs" (vs what we've in include, which has lots of stubbed out functions that are only required as symbols, but are never called)

15:12 <hannes> plus some functions to get gmp compiling..

15:28 <kakekongen> Anyone have used scrypt-kdf with hvt as backend? I get "undefined reference to `caml_salsa_core`" when compiling. It works as a charm for the unix backend. Any ideas?

16:54 <hannes> kakekongen: I suspect some cross-compile issues need to be sorted for salsa20-core then... depending on the build system (ocamlbuild/topkg -> nocrypto; dune -> checkseum)... since all the C code for MirageOS needs to be built with above mentioned includes and C library (rather than system libc) -- I can have a look at some point this week.