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How do I reinstall the original DSDT file?


stoomath
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So I've spent the last couple of days trying to get a wifi card to work, which eventually required changing the DSDT. I had never done this before, so was feeling my way through the process. In short, I inserted new code for the wifi card into the PCI1 section of the DSDT and inserted the new DSDT into /Extras. I neglected to make a backup of the original DSDT (and wasn't aware that you can tell Chimaera to use a different DSDT through the DSDT=[name] command.

 

Now when I boot into OSX (10.7.2), it says that pci0 isn't working, and to change to pci1 using the PCIRootUID flag. I've tried booting using the following commands:

 

PCIRoot=1

PCIRoot=0

-x

-s

DSDT=null

 

Nothing is working. I have arrived at the conclusion that I simply have to replace the DSDT.aml that exists in the /Extra folder, with the original DSDT for my motherboard. How would I go about doing this? I don't have a USB with Lion installed on it which I can boot from. I do have some SL system disks, if they would be of any use. I also have Windows XP installed, which works fine. Help would be greatly appreciated!

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Is there seriously no way to boot using a DSDT on a USB? I've been searching this for hours... all I did was replace the DSDT.aml with one that doesn't work... there must be a way to replace that file with the DSDT.aml for the MB. It was working fine before!

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Thanks I will try this now. Do you happen to know why the DSDT=Null command wouldn't be working? Given that this command should mean that the DSDT.aml in the /Extras folder is ignored, I'm puzzled as to why it doesn't allow me access to the system. Is it possible that changing the DSDT.aml as I did has also affected some other part of the system?

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If it's a DSDT.aml can't you just delete the file? I'm pretty sure editing the .aml doesn't actually change anything permanently it just tells chameleon to boot using that file instead of the regular DSDT table. Also I think the command should be DSDT=0 not DSDT=null. COuld be wrong about that tho.

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So where did you get the DSDT you were using before from? By your post, thinking maybe you have wrong impression of DSDT function in OSX. If you remove DSDT from Extra folder, bootloader will use your BIOS's true DSDT which you cannot change, edit or delete from the OSX finder. DSDT in extra folder is just a dump of the hardcoded one, so that edits can be made and load edited one instead of from the BIOS to assist with OSX hardware compatability. Placing an unedited DSDT in Extra should have no effect one way or another, as it would be the same as what your system will use by default. Since I don't think you hand edited the DSDT that was deleted, where did you get it from? If you did not put an edited DSDT into the Extra folder before adding the one that has started causing problems, just delete the new one and your done. If u can't get into OSX to delete it, boot in single user mode with "-s" at chameleon menu. at comand prompt follow instruction to mount / . then type"cd /Extra" hit enter and then type "rm DSDT.aml" hit enter and reboot. "-s" will not get you to the desktop, command line only, you'll see some text just like booting in verbose view then it will stop as if it froze, but you can type. works great for fixing stuff

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Thanks for the response. I originally had the DSDT.aml for my MB which I got from the Tonymac database in the /Extra folder. I hand edited the DSDT.aml, by inserting code with DSDT Editor in an attempt to get the wifi card working (as per instruction in the thread on it). I placed this new edited DSDT.aml into the Extras folder, replacing the original one, without making a backup of the original. I inserted the code wrong, which meant that the DSDT.aml wasn't allowing the system to boot.

 

I have since worked this out, if I hadn't had done it my way, the way you suggest above would have been my next move. Thankfully I had Windows XP installed on another partition, so all I did was go into XP, use Macdrive to explore the partition that Lion is installed on, navigated to /Extras, and replaced the DSDT.aml with the original one from the Tonymac database. System is now recovered.

 

What I still don't understand though, is why the DSDT=null function failed to boot into the system. If the problem truly was that the DSDT.aml that I edited was bad, surely this command would have ignored it. Maybe the system didn't want to boot using the BIOS's true DSDT that you refer to. Anyway, thanks heaps for the help, I'm learning things about this system one stressful day at a time :).

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