Re: Feature request: building musl in a portable way

[Nicholas Wilson <nicholas.wilson@realvnc.com>]

On 22 December 2017 17:49, Rich Felker wrote:
> A bit of a historical note on this: in the late 80s and 90s there was
> an effort called "iBCS" to make a unified ABI for Intel-based unices.
> I believe a common syscall layer was part of it. It was abandoned
> after everybody realized that the Linux syscall ABI _was_, for all
> practical purposes, the unified ABI they wanted.

That's pretty much where WebAssembly is going too! At the moment, the WebAssembly "embedding environment" (the webpage) has to provide a JavaScript implementation of the external dependencies of the WebAssembly module.

There is a desire to eventually standardise that a bit - at the moment it's "whatever Musl wants". I think the conclusion will be "emulate Linux everywhere". I'm expecting some small tweaks though. For example, traditionally timezone information is stored in userland and not available via a syscall: rather than special-case SYS_open for "/etc/localtime", we might add a Wasm-specific syscall for doing it. (Naturally, this would all be done in Wasm via an override in a Wasm-specific directory.)

So it will be "Linux syscalls" - but probably with a few tweaks (as indeed Linux syscalls already differ very slightly between architectures).

Nick