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I have seen various articles that describe how to install various versions of MacOs on x86 laptops from HP, Dell, etc.

Many of them refer to a need to patch the DSDT, and even recommend a gui DSDT patcher tool.

eg, google search result

or

alt text

Why is it necessary to patch the DSDT if I install MacOS on an HP laptop?

Would these patches also be necessary, or recommended, if I ran Linux or Windows on the same laptop?

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2 Answers 2

up vote 1 down vote accepted

According to the OSx86 Project:

The problem is that OS X has an incomplete ACPI implementation which supports only a subset of DSDT. Modifying the DSDT allows the user to better support their hardware. For example, fixing Time Machine and the UUID 35 error is possible after modifying the DSDT.

Also, according to ArchWiki (which is about Linux):

A common linux problem is missing ACPI functionality (fans not running, screens not turning off when the lid is closed, etc.) stemming from DSDTs made with Windows specifically in mind.

Hence, if both the above "OS X has an incomplete ACPI implementation" and your quote "HP generally seems to write exceptionally bad ACPI code" are true, then patching the DSDT might result in a better match, and thus make OS X work better with your non-Apple hardware?

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I run time machine perfectly fine without any DSDT modification. –  Robert S Ciaccio Dec 1 '10 at 16:23
    
@calavera, not every non-Apple computer is the same. –  Arjan Dec 1 '10 at 16:25
    
true enough, but it seems like every time I run into an issue I find people suggesting DSDT patching but I'm able to solve the problem with kexts. –  Robert S Ciaccio Dec 1 '10 at 16:28
    
ok I can buy explanation that MacOSX has a different or incomplete ACPI implementation, and this necessitates the DSDT change. Regarding the ArchWiki comment, I don't understand why "closing the lid" or "running the fan" is a MacOS or Linux thing, and not a Windows thing. People close the lids on Windows computers, probably... ah, every day! –  Cheeso Dec 1 '10 at 16:58
    
@Cheeso, because, apparently, many DSDTs [are] made with Windows specifically in mind. Hence: Windows can communicate very well with ACPI, but other OS's might not. Add to this that, apparently, the OS X implementation is bad too (maybe on purpose, to only support its own hardware) and the match between OS X and non-Apple DSDTs might be, errr, less than ideal? (But even then calavera might be right too: when using kexts that operate well with less than perfect DSDTs, there might not be a need to patch it at all.) –  Arjan Dec 1 '10 at 17:02

I've often wondered this as well and haven't found a good explanation. I consider myself as pretty advanced on the hackintosh subject at this point and I have a machine running perfectly without any DSDT patching...

There are so many good resources out there for kexts and other hacks that I tend to ponder whether this is even necessary anymore unless you are a complete perfectionist. The only thing my machine does not do is sleep, but I haven't even spent any time on trying to get that to work as it's a desktop machine that serves content to the household. It's been running for 45 days straight without so much as a hiccup (which is longer than I think I've ever had a PC run with windows), so do I really need to worry about DSDT?

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