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How to programmatically find out if computer is on

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Re: How to programmatically find out if computer is on

#141

Post by hackmiester »

Galanwe wrote: post #136
xyzzy_plugh wrote: post #130

Earlier quoted context omitted.

Is... this not how your WoL works? Hitting the NIC is equivalent to pressing the on button, boots the OS, etc. I've been using this for years to wake hosts at home when I'm abroad. It's invaluable.

For the sake of the argument, I think it's more of a shared capability of the motherboard _and_ the NIC, rather than the sole responsibility of the NIC. I wonder if that could be implemented solely by the motherboard. After all, it could supply a small amount of power to the NIC while shutdown and embed a minimal NIC driver to monitor incoming packets without the need for the NIC to do the monitoring itself.

I am not sure how this would meaningfully differ from the current state of affairs, where the NIC runs in a low power mode while the PC is off.

Re: How to programmatically find out if computer is on

#142

Post by OJFord »

1_player wrote: post #63
Waterluvian wrote: post #17

I’d like to see the unit tests for the non-true return state.

Result is undefined if computer isn't on, so any value is OK, no tests necessary.

GP said for the 'non-true state', not the 'computer off state'. I.e. verify that the computer is off, given that the fn returns false (which is valid only as part of its undefined computer-off response).

Re: How to programmatically find out if computer is on

#143

Post by batch12 »

slmjkdbtl wrote: post #93

I'm curious if there's any significance in number 0.63739 in this implementation double is_computer_on_fire(void) { return 0.63739; } https://github.com/haiku/haiku/blob/8f16317a5b6db5c672f33181...

Dunno. Referencing a US telephone keypad, it spells NERDY.

Re: How to programmatically find out if computer is on

#144

Post by qwerty456127 »

xyzzy_plugh wrote: post #130
lost_soul wrote: post #106

Earlier quoted context omitted.

I've often wondered why WOL is so poorly designed. WOL should be a function of the NIC, completely independent of the OS and capable of returning status codes even if the computer is "off".

Is... this not how your WoL works? Hitting the NIC is equivalent to pressing the on button, boots the OS, etc. I've been using this for years to wake hosts at home when I'm abroad. It's invaluable.

Now I'm almost curious if every PCI slot has a pin equivalent to the power button pin on the mainboard and also feed some basic background power to the cards even when turnt off. I doubt it actually is this simple though, the industry rarely chooses KISS.

Re: How to programmatically find out if computer is on

#145

Post by phlakaton »

jrumbut wrote: post #77
lifthrasiir wrote: post #54

While it is clearly a joke, it has a legitimate use as a syscall that does nothing so can be used to test the syscall process itself [1]. (Its cousin `is_computer_on_fire` is not a syscall.) [1] https://github.com/haiku/haiku/commit/ccaac177f64038c160de6f...

I was thinking the same thing, although in reverse: Imagine putting a few of these in as a joke and then you take it out and your parallelized code doesn't work anymore. Not sure how all that's handled on Haiku specifically.

is_computer_on_fire goes all the way back to the early days of BeOS IIRC. I'm sure full backwards compatibility has been _very_ carefully considered.

Re: How to programmatically find out if computer is on

#147

Post by Kaze404 »

This reminds me of the time when I had a TV attached to my computer through HDMI and I wanted to write a program that checked whether it was on or off. It turned out to be impossible, because even when it was turned off, it still appeared as connected on Windows because it was technically on stand by.

Re: How to programmatically find out if computer is on

#148

Post by zoomablemind »

p_l wrote: post #113
zoomablemind wrote: post #70

> is_computer_on() How does this relate to computer being in Halt state, which is quite valid state for servers (there could be even a dedicated Halt button)? Technically computer hardware is ON. I remember that in such state it shows a "carrot" prompt (>>>) from the SRE console. By the way, there is also HCF instruction (Halt and Catch Fire). https://en.wikipedia.org/wiki/Halt_and_Catch_Fire_(computing...

I admire for how you nerdsniped several other comments without anyone noticing the platform, or how "halt" would drop you into console monitor on said platform. My standing ovation to you :D (The platform is Alpha, right? Given the prompt and name for the console, though it was SRM, not SRE) :)

SRM it is. Thanks!

(Alpha) System Reference Manual:

https://en.wikipedia.org/wiki/System_Reference_Manual

Funny thing, for some historic reason, the system terminal attached to cabinet with those memorable Alpha Servers was of the monochrome lineage, but the phosphors color was orange. So the >>> prompt was unmistakably a carrot one! However it would rarely be seen, as bulk of the time the console would busily beep and boop with operator messages, as any respectful Alphas would be on 24/7/365 duty.

The only forced interruption I witnessed was when the attached storage controller froze. Literally. Someone left a window open in the server room, with -20C outdoors. So with all that circulation there was ICE accumulation on one side of storage controler cabinet. Apparently that put it beyond service temp range. Well, thawed it out - back to bizznizz, so to speak.

It that case, should've been is_system_iced() system call, it could've saved us the trip on such a freezing night. We would've just called HCF... briefly :)

Re: How to programmatically find out if computer is on

#149

Post by anonymfus »

qwerty456127 wrote: post #144
xyzzy_plugh wrote: post #130

Earlier quoted context omitted.

Is... this not how your WoL works? Hitting the NIC is equivalent to pressing the on button, boots the OS, etc. I've been using this for years to wake hosts at home when I'm abroad. It's invaluable.

Now I'm almost curious if every PCI slot has a pin equivalent to the power button pin on the mainboard and also feed some basic background power to the cards even when turnt off. I doubt it actually is this simple though, the industry rarely chooses KISS.

In PCI Express slot there is indeed a standby power (+3.3 V) pin and WAKE# signal pin, but it works differently than the power button.

https://en.wikipedia.org/wiki/PCI_Express#Pinout

The main difference is that WAKE# signal only restores power to the system but it does not change the system's power state, after using it the card needs to send an interrupt to the motherboard to properly wake it up. Power button does both things.

Re: How to programmatically find out if computer is on

#150

Post by eigen »

qwerty456127 wrote: post #144
xyzzy_plugh wrote: post #130

Earlier quoted context omitted.

Is... this not how your WoL works? Hitting the NIC is equivalent to pressing the on button, boots the OS, etc. I've been using this for years to wake hosts at home when I'm abroad. It's invaluable.

Now I'm almost curious if every PCI slot has a pin equivalent to the power button pin on the mainboard and also feed some basic background power to the cards even when turnt off. I doubt it actually is this simple though, the industry rarely chooses KISS.

there is a WAKE# pin on the PCIe slot so any card should be able to wake the system from sleep (S3).

however, an ATX PSU supplies only 5V (5Vsb) when the system is off (S5) which is not available on the PCIe connector which only has 12V and 3.3V. so when the system is off (S5), the PCIe cards are unpowered and thus cannot turn the system on.

but if you mean off in the Microsoft "Modern Standby" (S0i) then yes, the PCIe cards are powered and the WAKE# pin can "turn on" the system.

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