openbsd: add missing HW_* sysctl constants

[amrfti]

Adds missing HW_* sysctl constants.
The constants are defined in:
https://cvsweb.openbsd.org/annotate/src/sys/sys/sysctl.h

@rustbot label +stable-nominated

[rustbot]

Some changes occurred in a NetBSD-like module

cc @semarie

Some changes occurred in an OpenBSD module

cc @semarie

[semarie]

Do you really need all of these constants ? or it is just for completeness ?
As OpenBSD tends to deprecate and remove unneeded values across versions (and rust forbid this), I would prefer to expose only what it is really need to avoid future incompatibilities.

Additionallly, HW_MAXID would be unwanted (as the value will change very often).

Thanks.

[amrfti]

The only one I personally needed was HW_PHYSMEM64. The rest I added just for completeness. I still think some of the others should be added even if I didn't need them.

GuillaumeGomez/sysinfo#1318 for example needs several of these to gain support for OpenBSD.

[tgross35]

Could you add these to src/new/openbsd/sys/sysctl.h instead? We're trying to slowly reorganize. (feel free to move the existing HW_NCPUONLINE as well)

Also I suppose this list should ideally be restricted a bit based on @semarie's concerns

View changes since this review

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[tgross35]

As OpenBSD tends to deprecate and remove unneeded values across versions (and rust forbid this), I would prefer to expose only what it is really need to avoid future incompatibilities.

For what it's worth, I have no problem removing constants after a few releases if they are removed upstream. Or gating on the target_env version once we have that.

With that in mind I don't think the situation should be too different than anything written in C out-of-tree?

[amrfti]

Moving to src/new/openbsd/sys/sysctl.h I can do. I'm just not sure what all should be added/not added.

My use case was I need to write an OpenBSD fallback case for The Tor Project's Arti where we fetch the amount of system RAM using the sysinfo crate [1]. sysinfo doesn't support OpenBSD so I attempted to inline the libc calls myself but HW_PHYSMEM64 was missing. So all I need is that constant, but if sysinfo were to have OpenBSD support written... it would probably need many of these constants and others. I don't have an exhaustive list as I haven't attempted it.

Not familiar with best practices on bindings so I don't know how to decide what should{, not} be added, my instinct was a complete list.

[semarie]

From the list, it could make sense to have:

• HW_BATTERY
  • HW_BATTERY_CHARGEMODE
  • HW_BATTERY_CHARGESTART
  • HW_BATTERY_CHARGESTOP
• HW_BYTEORDER
• HW_CPUSPEED
• HW_DISKCOUNT
• HW_DISKNAMES
• HW_DISKSTATS
• HW_MACHINE
• HW_MODEL
• HW_NCPUFOUND
• HW_PAGESIZE
• HW_PERFPOLICY
• HW_PHYSMEM (unsure as it is deprecated in favor of HW_PHYSMEM64)
• HW_PHYSMEM64
• HW_POWER
• HW_PRODUCT
• HW_SENSORS
• HW_SERIALNO
• HW_SETPERF
• HW_UCOMNAMES
• HW_USERMEM (unsure as it is deprecated in favor of HW_USERMEM64)
• HW_USERMEM64
• HW_UUID
• HW_VENDOR
• HW_VERSION

Thanks.

[amrfti]

@rustbot ready

[semarie]

LGTM

View changes since this review

[tgross35]

Thanks! And thanks @semarie for reviewing

View changes since this review