Reflections on apm/apmd

[n_hologram]

I came across apm/ampd through openbsd. In openbsd, my experience with it is golden, because as far as I can tell, it does exactly what I want: suspend/hibernate as user (by default) with a console command, lid and power button functions, simple textfile configuration (I find acpi's events-for-shell-scripts approach to be more convoluted than apm's), and desktop-environment-amoral. With Linux, on the other hand, apm is "gradually being replaced by the ACPI standard," and I guess it makes sense given that, with the right adjustments, acpi can perform the same functions.

Nonetheless, apmd is still in the Debian repositories, and its kernel option still exists (albeit disabled by default). As recently as 2015, I can find posts about users who still used it, including one who tweaked his or her kernel in order to support it. However, I'm also aware that lots of changes Linux in general, and Debian and particular, have occurred in these last three years.

I haven't been able to find anything along the lines of "apm in openbsd vs linux", so it's nebulous how un-alike each operating system's own apm is compared to the other. I suppose the best answer would be, "recompile the stock kernel with apm enabled and see for yourself." However, dasein used to say that it's easier to learn from others' mistakes first; so I wanted to open it up here before I did any kernel-building for something that may end up being wholly undesirable.

Do you still use apm? Why?
Have you used it before and currently prefer acpi? Why?
What advantages does acpi have over apm that would be useful to know? (Maybe something more obscure, undocumented, that you found out "the hard way.")
If apm were enabled by default in your kernel, would you use it over acpi?
If you have any experience with openbsd, is there anything I should know about the linux/debian version vs. openbsd's?

[bw123]

Do you still use apm? Why? Have you used it before and currently prefer acpi? Why? What advantages does acpi have over apm that would be useful to know? (Maybe something more obscure, undocumented, that you found out "the hard way.") If apm were enabled by default in your kernel, would you use it over acpi? If you have any experience with openbsd, is there anything I should know about the linux/debian version vs. openbsd's?

No I don't still use apm,
My bios on any machine after about yr 1999 doesn't support apm,
Yes I used it on an older machine, with 1996 bios,
I like acpi because it works with newer bios on my machines,
The advantage, as I understand it, is acpi allows the os to enumerate and control devices instead of the bios,
I would use apm if it was the default and worked with my machine better than acpi,
I never used a bsd, but I have thought about it, are you sure they don't use an acpi-to-apm stub or some other patchy way to get the job done?

In general I really don't see it as a preference, are you saying apm and acpi are interchangeable just by enabling a kernel option?

As recently as 2015, I can find posts about users who still used it, including one who tweaked his or her kernel in order to support it.

I actually have a socket 939 machine very similar to the user in the thread you linked. It runs stretch and all the acpi related functions are fine, including 'cool N quiet' and the powernow-k8 driver handles the cpufreq correctly. I have never tried apm on it, and didn't really see where the post said anything about enabling a working apm setup on it?

[n_hologram]

Thanks for the information. All of that is incredibly helpful, especially knowing that apm flat-out won't work on newer machines. It also sounds like openbsd's version is very different from its linux counterpart.

I never used a bsd, but I have thought about it, are you sure they don't use an acpi-to-apm stub or some other patchy way to get the job done?

I'm not sure whether to infer "patchy" here as a negative or neutral term. With their focus on security, I imagine they would use a power management system that is fundamentally stable. However, it is possible that this is true. I asked for an account on daemonforums.org, but haven't heard back from their webadmins. HoaS or Garry might know.

Though I haven't used anything besides freebsd and openbsd, I know that the two OSes use different programs for their power management. Freebsd's acpiconf left something to be desired.