Using chameleon, how important is the DSDT file?

[Lord Anubis]

Hi,

Always, like you all, looking to get things right.

I did read that with 10.5.6+ and Chameleon we don't need the DSDT file anymore. f.e PCWIZComputer.com
Somewhere else they just talking about using that file.

Is this true, and what are your experiences?
Is maybe using or not using this file conflicting the [m]kext load?

Any comments on this

[Blackosx]

Hi Lord Anubis

I don't use a DSDT file, like you I read that it wasn't needed with 10.5.6 so I have never used one.

[Kabyl]

I did read that with 10.5.6+ and Chameleon we don't need the DSDT file anymore. f.e PCWIZComputer.com
Somewhere else they just talking about using that file.

It was needed in the beta releases of 10.5.6 because of the new AppleRTC kext, in the final release the bug was gone and so the so called RTC fix in the DSDT wasn't necessary.

On some PCs the DSDT has serious bugs and fixes are needed, sometimes you *want* to fix it to get things working like PM (Power Management) stuff.

Unfortunately, there is a lot of misinformation, so try to find a good source and don't believe everything you read!

[rocksteady]

I was also intrigued from the rumors about its necessity back in the day before the final 10.5.6 update. However, since it ended up not being necessary, I dropped my research.

I'm using a modified BIOS on my hack and so far (X.5.7) everything is smooth (as far as hacks go).  Besides the now invalid AppleRTC.kext buzz, if my memory serves me right, the very first thing a patched DSDT was supposed to solve, is Processor aliases (popular for Asus mobos) in order to get all cores working (or get them to work they way they should) in order to avoid certain kernel panics.

Another member has posted some useful info in this thread: [Solved] Difference in booting with and w/o DSDT verifying a popular thread @insanely about Chameleon's DSDT override capabilities.

For reference's sake, here's a short definition of the Differentiated System Description Table  from the official ACPI Spec:
"An OEM must supply a DSDT to an ACPI-compatible OS. The DSDT contains the Differentiated Definition Block, which supplies the implementation and configuration information about the base system. The OS always inserts the DSDT information into the ACPI Namespace at system boot time and never removes it."

but as the LinuxACPI project states:
"Unfortunately, many hardware vendors and OEMs are not capable of supplying fully functional tables (not even the members of the ACPI SIG).", which pretty much sums up why most of the hacks would benefit from a decently patched DSDT file.

Anubis, if you'd like to maintain this thread and come up with useful info I'd be happy to start researching DSDT again (as time permits). An easy+fast solution would be to integrate the info from the thread above into this one (I should move it anyway as its not part of the bugs).

[Gringo Vermelho]

Since 10.5.6, ASUS P5Q series boards can't boot OSX without the CPU aliases removed from the DSDT table.

So a patched DSDT is needed if you own one of those boards.

The patched BIOS files you can find for running OSX have the CPU aliases removed in the DSDT. It's convenient to use a patched BIOS but it can be risky and it's not as flexible as using DSDT.aml.

What's more, if you have near-compatible on-board sound, LAN and graphics you can add your hardware to the DSDT table and run without patched kernel extensions or third party drivers for that hardware.

It's a bit of a black art though. More voodoo than voodoo.

http://www.insanelymac.com/forum/index.php?showtopic=142434
 

[Lord Anubis]

Anubis, if you'd like to maintain this thread and come up with useful info I'd be happy to start researching DSDT again (as time permits). An easy+fast solution would be to integrate the info from the thread above into this one (I should move it anyway as its not part of the bugs).

I did read in earlier info about DSDT, and not convinced that it is the holy grail.
After that I was curious what kind of influance DSDT has on the loading state of device id added modified kexts.

If DSDT is not needed anymore then IMHO Guess, it will'be a waste of time to do more research about it.

Thanks

[Blackosx]

I don't use a DSDT file, like you I read that it wasn't needed with 10.5.6 so I have never used one.

How different things were for me back in May......   
Since then I read up on it, learnt how to build one and now I have a better system because of it.

[18seven]

Love it. IMO its a much cleaner than kext patching and offers many benefits otherwise missed. I just used it to enable hyperthreading with native ApplePowerManagement and looking forward to being able to utilize GCD in 10.6.

[Gringo Vermelho]

That sounds cool, please post how you did it.

[18seven]

Change the processor scope to system bus. Search for "Processor" change Scope (_PR) to Scope (_SB). Follow up on CPUs reference i.e search "CPU0" change each instance of \_PR.CPU0 to \_SB.CPU0, same for CPU1, CPU2, etc.. Declaring PR is default for legacy support, not current spec. Declaring SB also supports objects needed to enable native speedstep, at least that is my understanding.

Slightly ot but if anyone can ioreg dump a mac with Intel Xeon “Nehalem” processor or direct me to one already posted, it would be appreciated.

[Lord Anubis]

With 10.5.8 and the current chameleon version in mind, what is the best tutorial to get DSDT right?

I see several but always with complaining comments.

Thank you.

[Blackosx]

Hi Lord

I followed koalala's ACPIPatcher guide on Insanely. (showtopic=142434). It's a windows application but doesn't need to be run on your hack, a different windows machine will work. I have written a simple guide to help show the basics. It's no master class, but it gives an introduction to building a DSDT.aml. It's for the GA-EP45-DS3L, but the principle will be the same for your mobo. It's on insanely (showtopic=177497).

For different techniques and more advanced info, I am sure others here will be able to help.

[Gringo Vermelho]

Change the processor scope to system bus. Search for "Processor" change Scope (_PR) to Scope (_SB). Follow up on CPUs reference i.e search "CPU0" change each instance of \_PR.CPU0 to \_SB.CPU0, same for CPU1, CPU2, etc.. Declaring PR is default for legacy support, not current spec. Declaring SB also supports objects needed to enable native speedstep, at least that is my understanding.

The only instance of _PR in my DSDT is at the beginning, at the part where you remove the CPU aliases. I can't find any other references to CPU0, 1, or \PR.CPU0, 1 etc.  anywhere else either. So I changed it to _SB, rebooted and it locked up during boot, sometime after this message (which I've never seen before):

ACPI_SMC_PlatformPlugin :: PushCPU_CSTData - _CST Evaluation failed

Then I tried disabling "CSTATE-tech" in the BIOS but then it locked up at initialization of AppleIntelCPUblabla instead.

I have to say that I love how easy it is to test these things with a Chameleon boot CD.

My CPU is a Core 2 Duo E8500 which doesn't have Hyperthreading of course but it would be cool to get native speed stepping working. If you do more research on this, please keep us posted.

Output from sysctl -a | grep freq:

kern.exec: unknown type returned
hw.busfrequency = 1332000000
hw.cpufrequency = 3160000000
hw.tbfrequency = 1000000000
hw.tbfrequency: 1000000000
hw.cpufrequency_max: 3160000000
hw.cpufrequency_min: 3160000000
hw.cpufrequency: 3160000000
hw.busfrequency_max: 1332000000
hw.busfrequency_min: 1332000000
hw.busfrequency: 1332000000

About the ioregs you're looking for, there's a thread at the ProjectOSX forums with attached dumps from real macs. I don't know if there are any Nehalem dumps available yet though.

[00diabolic]

I have been doing some googling and found this topic. After reading, I just have one question about DSDT. DSDT is ACPI tables from the bios. Does the DSDT also include information about your CPU?

From what I read it covers p states for speed step and ram information but is that it? What about cpu speed information? Does the DSDT have that information in it and can it be edited if your bios provides the wrong information about your cpu like with the ASUS bioss and the cpu alias fix mentioned above?

I have looked in my own DSDT but I cant not find information about my cpu. Maybe I dont know what to look for. Is it even there?

[valv]

@00diabolic,
you are not looking in the right place. cpu states are declared in SSDTs. most are hidden from osx, that's u should dump 'em from linux or windows (if u don't know how, I made some guide on insanelymac (showtopic=215233)). Once u get those tables, look into _PSS section.