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View Full Version : downgrade to SL from Lion using restore usb key




hexproject
Jul 22, 2011, 12:08 AM
hi, just got a 2011 machine with Lion.
But not ready for Lion because some apps may not work.

I am using a 2010 MBA right now that came with the white USB recovery Key.
I am trying to load the USB key... but seem likes that doesn't work...

any ideas on how to revert the new MBA 2011 to 2010 SL using the recovery key???



TheEmpty
Jul 22, 2011, 12:13 AM
Snow won't have the drivers for the new hardware. You can't run it. Out of curiosity, does anyone know why certain applications don't work anymore? Is it just old hooks or something?

hexproject
Jul 22, 2011, 12:17 AM
really? that's interesting.....

so new hardware can't run SL at all?
that kind of sucks.. so that forces you to upgrade or be stuck,...

ShiftClick
Jul 22, 2011, 12:33 AM
Welcome to mac computers, yes it pretty annoying.

jmazzamj
Jul 22, 2011, 12:47 AM
hi, just got a 2011 machine with Lion.
But not ready for Lion because some apps may not work.

I am using a 2010 MBA right now that came with the white USB recovery Key.
I am trying to load the USB key... but seem likes that doesn't work...

any ideas on how to revert the new MBA 2011 to 2010 SL using the recovery key???

You will never be able to use your USB recovery key with any Mac it did not ship with and there's no way around it. It only works with 2010 Airs.

The only way to install Snow Leopard in a 2011 Air would be cloning a 10.6.9 updated SL, which I don't think Apple will ever release and it is unlikely to work in a 2011 Air anyway.

Buying a new Mac along the release of a new OS sucks for that very reason...

ChiSnowman
Dec 5, 2011, 03:09 PM
Is it possible to downgrade if you have a 2010 MBA using the USB stick? I have Lion installed on mine but have heard conflicting answers on whether it's possible to go back to SL. I do not have a Time Machine back up of SL before I upgraded either.

oneMadRssn
Dec 5, 2011, 07:32 PM
Is it possible to downgrade if you have a 2010 MBA using the USB stick? I have Lion installed on mine but have heard conflicting answers on whether it's possible to go back to SL. I do not have a Time Machine back up of SL before I upgraded either.

Yes. You can always downgrade to the earliest OS your model computer ever came with.

For example, the current MBP ships with Lion, but the same models did ship with Snow Leopard before Lion came out so they can be downgraded.

I too want to downgrade my 2011 MBA to SL.... Lion is lame.

monkeybagel
Dec 5, 2011, 07:52 PM
From experience, I can tell you the 2011 does not play well with Snow Leopard. Even if you do get it to install, it will not have accelerated graphics, nor full trackpad functionality. It also will run much slower - it doesn't appear to manage the processor speed correctly (turbo boost technology, etc.).

monkeybagel
Dec 6, 2011, 12:52 AM
Looks like a solution to the speed problem:

https://discussions.apple.com/message/16916075#16916075

oneMadRssn
Dec 6, 2011, 09:16 AM
For reference: (all credit goes to newfoundglory on apple discussions)

I don't have ANY issues with Snow Leopard on my Mac mini 2011 quad server.

I am not convinced that using a retail disk is a good idea - when I have tried that in the past with other Macs it never got all the drivers and never added all of them after a Software Update either!

I used 10.6.8 (10K549) from my MacBook Pro (Early 2011), as it has exactly the same hardware as a quad-core mini. No boot problems with this, all drivers working good. I actually used carbon copy cloner to an SD card at first, and booted off that before I restored it to the mini server's second hard drive.

BUT there are serious performance issues, as Snow Leopard doesn't seem to speedstep the processor correctly with a machine identifying itself as being a Macmini5,x, so any of:
Macmini5,1 - dual core with Intel HD3000 graphics
Macmini5,2 - dual core with AMD graphics
Macmini5,3 - quad core i7 (server)

Basically to fix this you need to modify a kernel extension, and update the caches - You need access to a copy of Lion for this - I used the copy of Lion which came preinstalled on the second hard drive.

USING the Lion partition (either using Finder > Go to folder…, or by using the Terminal) you need to go to:
/System/Library/Extensions/IOPlatformPluginFamily.kext/Contents/PlugIns/ACPI_SMC_PlatformPlugin.kext/Contents/Resources/

FIND Macmini5_1.plist, Macmini5_2.plist or Macmini5_3.plist (depending on your Mac mini 2011 model, or copy all of them if you aren't sure).

COPY these back to the the same location on your Snow Leopard partition.

REMEMBER, depending on how you copy the plist file(s) you may have to change ownership of the file(s). The plist file should be owned by root and the wheel group on Snow Leopard.
Using Terminal and Snow Leopard partition:
sudo su -
[enter your admin password]
cd /Sy*/Li*/Ex*/IOPla*/Con*/Pl*/AC*/Con*/Res*/
chown root:wheel Macmini5*

EDIT:
Necessary(?) command to do after chown root:wheel Macmini5*:
chmod 644 Macmini5*

FINALLY, update the kernel caches using Terminal by typing:
kextcache -system-prelinked-kernel
kextcache -system-caches

THEN, reboot your Mac mini!!
from the link above.

I am willing to try this on my 2011 MBA in a few weeks, after I am done with finals. However... I had a few concerns:

- The early 2011 MBP he suggests borrowing the OS from has the requisite Intel HD 3000 graphics, but it does not have the same class of processors (ours are ULV). This might be a problem, but perhaps swapping the kext as suggested above would fix this. Thoughts?

- Other hardware differences? Blade SSD? Thunderbolt?

monkeybagel
Dec 6, 2011, 02:37 PM
For reference: (all credit goes to newfoundglory on apple discussions)


from the link above.

I am willing to try this on my 2011 MBA in a few weeks, after I am done with finals. However... I had a few concerns:

- The early 2011 MBP he suggests borrowing the OS from has the requisite Intel HD 3000 graphics, but it does not have the same class of processors (ours are ULV). This might be a problem, but perhaps swapping the kext as suggested above would fix this. Thoughts?

- Other hardware differences? Blade SSD? Thunderbolt?

The main problem I got was video acceleration. I did try it but the bottom of the Air got uncomfortably warm so I shut it down. Still not hardware video acceleration. That is the main sticking point it looks like. Not sure what the CPU was doing - I do know Spotlight was indexing, but it was so warm I was a little uncomfortable leaving it that way knowing the SMC kext just might no be playing nice with Snow Leopard. There are a few differences - one being an internal display of course. This is where one of the sticking points are. If the the internal display does not work (LED backlight illuminates, but that's all) unless you change around some of the kext files. When that is done, it seems they load enough to provide video but not acceleration. When you look at the console, it is trying to access APIs that are not there and the video drivers to not load. I will mess more with it later, but that is where I am right now.

Since the mini has only external video, it seems that the kexts are for external video. If you connect the Air to an external monitor, you can see the video on 10.6.7 or 10.6.8.