|
ACPI - what do you know about it?
#237819 - 11/01/10 10:21 PM
|
|
|
I found this about it in Wiki:
Quote:
Linus Torvalds, creator of the Linux kernel, once described it as "a complete design disaster in every way", in relation to his view that "modern PCs are horrible".
Thoughts, ideas, rantings....?
|
Consider it high comedy....sincere tragedy....whatever...don't take it personally.
The Culture
|
|
| Pi |
|
Allergic to life
|
|
|
|
|
Reged: 09/20/03
|
|
Posts: 6449
|
|
Loc: Room 101
|
|
|
|
Send PM
|
|
|
Re: ACPI - what do you know about it?
[Re: mogli]
#237822 - 11/02/10 12:06 AM
|
|
|
> I found this about it in Wiki:
>
> Linus Torvalds, creator of the Linux kernel, once described it as "a complete design
> disaster in every way", in relation to his view that "modern PCs are horrible".
>
> Thoughts, ideas, rantings....?
I don't have a direct experience with it, but I know of someone who had a couple of things to say about it while programming something under Gentoo IIRC, about two years ago. As with some other "niceties", ACPI is just a convoluted patch over a whimsy solution for an unsolved problem due to a limitation of the original PC specs; from that point of view I can agree that modern PCs are horrible because there are lots of stuff to avoid, implement, solve or patch tons of legacy. IIRC the problem with ACPI is that exact implementation varies, there are several versions, and not all programs dealing with ACPI APIs for certain languages or OSes are fully compatible so results could be unexpected.
This guy said that ACPI could be safely configured from the bios and then left untouched unless your program is vendor specific (e.g. laptops) where they know what they can expect from their ACPI implementation. Personally I never used any of the power configuration stuff from ACPI controls so it has been useless for me since the very first PC I got which had this seemingly cool ACPI stuff which would turn off the monitor after an interval and those things.
edit: Forgot to tell that this guy said that after some research he recommended the company to avoid ACPI and search other solutions, as he had lots of headaches reading ACPI documentation, specs, etc.
|
Wound up, can't sleep, can't do anything right, little honey / Oh, since I set my eyes on you. / I tell you the truth.
I can't get it right / Get it right / Since I met you...
|
|
| Sune |
|
Connected
|
|
|
|
|
Reged: 09/21/03
|
|
Posts: 5648
|
|
Loc: Lagoa Santa, Brasil
|
|
|
|
Send PM
|
|
|
Re: ACPI - what do you know about it?
[Re: mogli]
#237827 - 11/02/10 01:43 AM
|
|
|
> I found this about it in Wiki:
>
> Linus Torvalds, creator of the Linux kernel, once described it as "a complete design
> disaster in every way", in relation to his view that "modern PCs are horrible".
>
> Thoughts, ideas, rantings....?
Why do you ask?
Some manufacturers optimize the ACPI code for Windows only and compile it using Microsoft's ACPI compiler. Then sometimes you have to manually fix and recompile your ACPI tables to get power management properly working on Linux. There are whole forums dedicated to this discipline.
Those who have studied the ACPI specs pdf extensively all say that Hewlett Packard write some of the worst ACPI code in the world.
Some really nerdy stuff you can do if you're curious:
Make sure ACPI 2.0, ACPI APIC and all CPU features (Except CPU ID limit, which is for backwards compatibility with old OS such as Windows 98) are enabled in your motherboard BIOS settings. While you're there, if you're using a 64-bit OS, set the HPET to 64-bit, if you have such a setting.
On Windows, you can dump your ACPI tables with Everest Corporate Edition, and decompile them using IASL: http://www.acpica.org/downloads/binary_tools.php
Try decompiling your DSDT table with IASL, then compile it and see how many errors and warnings you get. I can almost guarantee you it won't be pretty.
You can boot from a Linux Live CD (Mint for example), open a command prompt and type dmesg|grep ACPI to see what's working and what isn't. I haven't played around with this much but I know there are various boot flags that enables and disable ACPI features. Linux Mint for example is set to use a minimal ACPI feature set to avoid compatibility issues. I guess this is probably true for most Linux distros.
If you're using Windows 7 (probably Vista too) start an elevated command prompt, navigate to the root of your drive and type powercfg -energy. an "Energy Report" will be saved to the root of your drive.
When doing this, I get this message, once for each CPU core: "There is a problem with the definition of the ACPI _PSD object on this computer. Installing the latest system firmware (BIOS) may resolve this issue". The PSD code has to do with CPU power state switching and is part of the SSDT ACPI tables.
Download and install the "Windows driver kit" and run pwrtest /info:ppm. This will show all available P- and C-states for your CPU.
S
|
|
|
|
Re: ACPI - what do you know about it?
[Re: mogli]
#237873 - 11/03/10 12:23 AM
|
|
|
ACPI is designed to solve several real problems, including that PC hardware required for minimal functionality has become increasingly complex and varied, modern CPUs are often capable of operating in multiple incompatible modes and there are a number of radically different operating systems in common use. Something needed to be done about it. ACPI is over-engineered and ugly - there are other, more elegant solutions to the same problems, such as Open Firmware. But ACPI isn't fundamentally flawed - it could do what it says on the can.
The problems are, of course, in implementation. The initial implementation of ACPI support in Windows was completely broken, but it was the first major operating system to support ACPI in any way. Hardware manufacturers started adding ACPI features, but rather than targeting the standard, they targeted Microsoft's broken implementation. As a result, a lot of hardware won't work with a compliant ACPI implementation, and OS developers are stuck trying to emulate Microsoft's broken implementation in order to provide compatibility with these devices. (Kind of like browser vendors emulating the quirks of other browsers so that poorly written HTML/CSS would display how the user expected.)
As for Linus, he's great at whining about problems without offering workable solutions.
|
|
|
|
A combined response
[Re: Pi]
#237885 - 11/03/10 02:57 AM
|
|
|
I'm still using a late-model P4 and XP 32-bit. I didn't really understand the particulars of what Wiki said, so I wondered what kinds of response I'd get here. Elsewise, I wanted to see how my user experience might differ with it enabled. There were only two parametres avaialable - ACPI 2.0 support, and ACPI ACIP support - both of which are enabled. I don't know as I've experienced anything different yet.
|
Consider it high comedy....sincere tragedy....whatever...don't take it personally.
The Culture
|
|
| Sune |
|
Connected
|
|
|
|
|
|
Reged: 09/21/03
|
|
Posts: 5648
|
|
Loc: Lagoa Santa, Brasil
|
|
|
|
Send PM
|
|
|
Re: A combined response
[Re: mogli]
#237890 - 11/03/10 07:01 AM
|
|
|
> I'm still using a late-model P4 and XP 32-bit. I didn't really understand the
> particulars of what Wiki said, so I wondered what kinds of response I'd get here.
> Elsewise, I wanted to see how my user experience might differ with it enabled. There
> were only two parametres avaialable - ACPI 2.0 support, and ACPI ACIP support - both
> of which are enabled. I don't know as I've experienced anything different yet.
ACPI 2.0 support is normally disabled by default in AMIBIOS, which means there's a good chance that XP was installed on your PC with it off.
I saw somewhere that it should be enabled before installing Windows for it to work properly, something about IRQ routing. I don't know..there's a lot to read and most of it is over my head.
S
|
|
|
| Pi |
|
Allergic to life
|
|
|
|
|
|
Reged: 09/20/03
|
|
Posts: 6449
|
|
Loc: Room 101
|
|
|
|
Send PM
|
|
|
Re: ACPI - what do you know about it?
[Re: Vas Crabb]
#237898 - 11/03/10 12:20 PM
|
|
|
> As for Linus, he's great at whining about problems without offering workable
> solutions.
Aren't we all? ^_^
|
Wound up, can't sleep, can't do anything right, little honey / Oh, since I set my eyes on you. / I tell you the truth.
I can't get it right / Get it right / Since I met you...
|
|
|
Re: A combined response
[Re: Sune]
#237915 - 11/03/10 04:48 PM
|
|
|
> > I'm still using a late-model P4 and XP 32-bit. I didn't really understand the
> > particulars of what Wiki said, so I wondered what kinds of response I'd get here.
> > Elsewise, I wanted to see how my user experience might differ with it enabled.
> There
> > were only two parametres avaialable - ACPI 2.0 support, and ACPI ACIP support -
> both
> > of which are enabled. I don't know as I've experienced anything different yet.
>
> ACPI 2.0 support is normally disabled by default in AMIBIOS, which means there's a
> good chance that XP was installed on your PC with it off.
> I saw somewhere that it should be enabled before installing Windows for it to work
> properly, something about IRQ routing. I don't know..there's a lot to read and most
> of it is over my head.
>
> S
APIC, not ACIP. It's also IRQ routing related.
|
|
|
|
|
Yeah, I dyslexed that one. Anyways, yes, far as I know, they were both disabled when I got the PC. Just in the last few days have they been enabled. Still not sure there's been any difference in performance.
>
> APIC, not ACIP. It's also IRQ routing related.
|
Consider it high comedy....sincere tragedy....whatever...don't take it personally.
The Culture
|
|
| Pi |
|
Allergic to life
|
|
|
|
|
|
Reged: 09/20/03
|
|
Posts: 6449
|
|
Loc: Room 101
|
|
|
|
Send PM
|
|
|
Re: A combined response
[Re: mogli]
#238015 - 11/04/10 04:59 PM
|
|
|
> Yeah, I dyslexed that one. Anyways, yes, far as I know, they were both disabled when
> I got the PC. Just in the last few days have they been enabled. Still not sure
> there's been any difference in performance.
I don't think that there is any difference in performance as ACPI doesn't address anything about that. Just things like power savings, shut down hard disks after a period of inactivity, etc.
|
Wound up, can't sleep, can't do anything right, little honey / Oh, since I set my eyes on you. / I tell you the truth.
I can't get it right / Get it right / Since I met you...
|
|
|
Re: A combined response
[Re: Pi]
#238082 - 11/05/10 07:27 AM
|
|
|
> > Yeah, I dyslexed that one. Anyways, yes, far as I know, they were both disabled
> when
> > I got the PC. Just in the last few days have they been enabled. Still not sure
> > there's been any difference in performance.
>
> I don't think that there is any difference in performance as ACPI doesn't address
> anything about that. Just things like power savings, shut down hard disks after a
> period of inactivity, etc.
No no, I didn't mean 'performance' performance, but general usage...although, by the way it read in Wiki, I was thinking it might affect how peripherals were handled.
|
Consider it high comedy....sincere tragedy....whatever...don't take it personally.
The Culture
|
|
Previous 
Index 
Next 
Threaded 
ACPI - what do you know about it?
Reply
[Re: 
