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Re: [PATCH] Add apple_set_os command


From: SevenBits
Subject: Re: [PATCH] Add apple_set_os command
Date: Tue, 7 Jan 2014 18:04:35 -0500

On Jan 7, 2014, at 10:19 AM, address@hidden wrote:

> Am 2014-01-03 19:38, schrieb SevenBits:
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>> On 01/03/2014 01:46 AM, Vladimir '?-coder/phcoder' Serbinenko wrote:
>>> On 31.12.2013 00:11, SevenBits wrote:
>>>> On Monday, December 30, 2013, Andreas Heider wrote:
>>>> The EFI on current macbooks configures hardware differently
>>>> depending on wether it is booting Mac OS X or a different os, for
>>>> example disabling the internal GPU completely on some models.
>>>> Mac OS X identifies itself using a custom EFI protocol.
>>>> This adds a command that fakes the os identification, making all
>>>> hardware accessible.
>>>> Just a question: I do a lot of booting Linux on MacBooks, and I
>>>> frequently suffer from this issue. How do we know that this code
>>>> actually works?
>>> Run on a mac with this code and without and compare results. The
>>> ship of "works by sane design" has long since sailed away. For
>>> most manufacturers it's somewhere in Moon orbit but for apple it
>>> has long since left solar system.
>> So, Andreas, I tried your patch, and... no dice. The Mac behaves
>> exactly as before. I'm afraid it didn't appear to do anything for me.
> 
> Hi,
> thanks for testing! I suspect that your MacBook Pro is simply too old. I 
> don't know exactly when this protocol was introduced, I found references to 
> it on Hackintosh-Forums from a while ago and in the Mac OS X internals book 
> which is also a bit older.
> 
> What effect exactly were you looking for? Your MBP doesn't have a second GPU 
> to disable.
> Also, AFAIK the older models disable less hardware when you boot via EFI than 
> the newer ones, since Bootcamp with EFI wasn't supported.

I was looking for any change in the video behavior. You are correct that my MBP 
does not have a second GPU, but I was looking for any change at all that might 
indicate the patch worked.

Anyway, the patch didn’t work on my machine, so I guess the point is moot.

> 
>> Furthermore, your patch didn't print any output. There wasn't any
>> error message returned (i.e your "Could not locate the apple set os
>> protocol." message on line 52-53). When I invoked your command from
>> the GRUB normal prompt, it DID print the message however. Perhaps it
>> doesn't fail if called from within a grub.cfg, or maybe it simply
>> doesn't print.
> 
> If it prints something on the promt I'd say it's working as intended, 
> although I'm pretty sure that I see output from it when I boot a grub.cfg 
> entry.
> 
>> The Mac that I tested on was a MacBook Pro from early 2008. Clearly,
>> this function isn't present on all models. I can try it on others and
>> seeing if it works on them, however.
> 
> If you have the time, please do. I'd be interested in what exactly changes.

Perhaps it would be a good way to see which MBPs have this protocol as well.

> 
>> Also, why the if statements on lines 59 and 65, which indicate whether
>> the OS version and/or vendor was set. What is the point of them? Why
>> not just call the functions directly?
> 
> It's just some output so you know that the command did something.
> 
>>> _______________________________________________ Grub-devel mailing
>>> list address@hidden
>>> https://lists.gnu.org/mailman/listinfo/grub-devel
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