[Rust-VMM] interest in other Unixes?

Allison Randal allison at lohutok.net
Wed Apr 15 20:39:03 UTC 2020

Hi all,

How interested would you be in patches for Unix family operating systems
other than Linux? I'm working on a prototype lightweight VMM on the
Illumos Kernel and Bhyve ioctl interface, and I'm planning to reuse
rust-vmm libraries where I can. I prefer to work upstream on shared
libraries, but I totally understand if the focus here is Linux, and
patches for other Unix family operating systems are undesirable.

As a concrete example of how non-disruptive this can be, the patch I'm
debating whether to submit is a 4 line substitution in vmm-sys-util,
which changes [#cfg(unix)] to [#cfg(linux)]. Right now, those lines are
checking for target_family = "unix", but the code in question is
actually unique to Linux, and fails to compile on other Unix family
operating systems (mostly due to type errors, and using features that
only exist on Linux), so it really should be checking target_os =
"linux" instead. The specific changes are lines 8, 17, and 19, in
src/lib.rs, which determine whether to use the code in the
architecture-specific 'unix' directory, and whether to use the bitflags
library (which is only used by the 'unix' directory). And, line 183 in
src/errno.rs testing a very specific string message as the text for
libc::EBADF, which has slightly different wording on other Unix family
operating systems.

That simple substitution makes it possible to use both vmm-sys-util and
vm-memory on Illumos (since vm-memory was only using
architecture-independent parts of vmm-sys-util for temp files in tests,
and nothing in the 'unix' directory). I haven't started systematically
testing other rust-vmm libraries for non-Linux compatibility yet, but I
expect I'll find similar patterns.

(Full disclosure: I personally prefer Linux Kernel and KVM, but this is
paid work, and sparks enough intellectual curiosity for me to be willing
to do it.)

Thanks for any thoughts,

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