Install Snow Leopard on new MacBook Air?

I've managed to install Snow Leopard on a new MacMini. Kind of a hazzle, but it works. Just ordered an MBA 11" on Black Friday, and I really hope I can squeeze in Snow Leopard somehow, perhaps using kexts from Mac OS X Vista (Lion).

PLEEEEASEEEEEE let me know how you're doing.

my buy depends on this...

yesterday i was trying it again at the store, but lion drives me mad...😟

I do not know about Snow Leopard, but you can certainly install Linux. Pick a distro, load the Live CD/USB stick (you'd obviously need an external CD/DVD drive for the former), boot from it by holding down the option key when starting, and you can choose to dual boot, or wipe the drive and install only Linux.

The boot loader will get replaced by the Grub bootloader.

It is easy.

matthew243 wrote:

I do not know about Snow Leopard, but you can certainly install Linux.

You can install Windows too, but as the OP wants Snow Leopard this is as useful as suggesting Linux.

Graf i need to ask you about MBA 2011 Lion install. email me vseae15o@gmail.com

Did you manage to install 10.6.8 on your Macbook Air? I managed, but I have some screen problems because I do not have the right drivers (I think) for the Intel HD 3000 Graphics. I of course see the kext files, but if I move them to

/System/Library/Extensions

I get a message that this is not going to work...

Any good tips on this?

Thanks

Well... this is a bit late (for obvious reasons) but worth posting since it's the first thread I came up with when searching for a solution to the same problem.

I've tried a slightly different route (bravely...) - my main portable Mac was one of the first 11" Macbook Airs, souped up with an OWC Mercury Aura Pro Whatsit Bollox 240 GB (apologies, but insanely long marketing names wind me up). Anyway, the name aside, it's a brilliant upgrade - basically a SandForce controller with 7-8% overprovisioning (i.e. chip capacity reserved for block organisation and wear levelling algorithms, making the already-fast SandForce SSD controller work optimally even when there are no spare blocks left - they assume that TRIM won't be supported, although it's hackable even in Snow Leopard). The hot-running SandForce controller chip has a thermal transfer pad stuck to it, which is in contact with the bottom aluminium panel when re-assembled, acting as a heat sink. I'm no OWC shill but my first-gen 11" Air, with this fast SSD, worked brilliantly as my main on-site business machine - even when adding a VMware instance of WinXP with MSSQL and some computationally intensive investment risk analytics software on top of the everyday OS X app footprint (MS Excel, Safari, Mail, PIM stuff, dev tools, and a lot of Terminal windows along with MacPorts CLI tools).

Back on topic... I've only got the MacBookAir4,1 due to duff luck (or lack of patience). The most critical thing to me is RAM... my dream Air would have 8 GB of RAM, and a SandForce SSD upgrade. It didn't look as if Apple was going to let the 11" Air have 8 GB of RAM... and the i5 hyperthreading *does* make a difference to my app workflow, and I missed the backlit keyboard from my old 13" MacBook Pro. So I bought the Air4,1 - knowing I could move the old Air's upgraded SSD across. Argh... As is typical, if I'd waited for a couple of months, I could have specced an 11" Air with a 2.0 GHz Intel i7 and the Most Wanted 8 GB of RAM. Argh. That said, the OWC SandForce SSD wouldn't fit the MacBookAir5,1 model and I'd have to buy a bunch of MagSafe2 -> MagSafe adapters to deal with all my existing MagSafe charging points (all the adapters, and a couple of Apple octopus-cable LED Cinema displays). The expensive part would be getting the fast SSD... with Apple's OEM SSDs being allegedly randomly chosen between Samsung and Toshiba, and there being a large performance difference between them (for my I/O-bound apps), I'd want to install another OWC SandForce SSD. Can't afford the £2k that a new CTO 11" Air (with i7 CPU and 8 GB RAM, and a new SandForce SSD upgrade from OWC) would cost me right now, so back to the MacBookAir4,1...

Basically I already had a full Snow Leopard 10.6.8 system, fully patched, with apps and preferences, on an upgraded stick-type MacBook Air SSD. The OWC SSD-stick I bought for the Air3,1 is compatible with both the nVidia chipset C2D 11" Airs and the Intel chipset i5 11" Airs (up to MacBookAir4,2). It's only capable of SATA3 max streaming speed - whilst the Intel chipset is SATA6 - but a single SSD won't trouble the bus. So all I had to do was remove the bottom panel from both machines, switch the SSD-sticks, plug the 'new' Air into the old one's USB gigabit ethernet adapter, boot up and hope!

Actual enclosure disassembly, SSD-stick replacement and enclosure reassembly was trivial - though you need the pentalobe screwdriver. With the case bottom removed, the SSD-stick socket and retaining screw looked identical, as did the battery. The earlier machine had two pressure points for the heatpipe (clearly the Intel CPU and the nVidia integrated northbridge / GPU), whereas the newer machine only had one (since the Intel i5 does both CPU and GPU jobs). The 'user replaceable' parts - limited for most users to the SSD and WiFi / Bluetooth card - were easy to access, and the SSD swap took less than 5 minutes. The 128 GB Apple SSD (which was Samsung, BTW) was switched from the Air4,1 to the Air3,1 - and the OWC 240 GB SandForce stick was installed in the 'new' machine.

Hence, with no fresh Snow Leopard installations, or any 'downgrade' of the included Lion OS (which I'll be skipping due to the feedback I've heard) - basically the entire Snow Leopard 10.6.8 system from the older model was *physically* transferred into the newer model. No migration assistants, no kext hacking (yet).

With the SSDs swapped, the newer i5 machine booted up without any noticeable problem... other than a black screen. The LED backlight was clearly (heh) on full. The backlit keyboard was lovely and bright. But no display was shown on the laptop screen.

It didn't look like a hard-lock, and no kernel panic text was visible, so I logged in across the network. Remember that I'd pulled the SSD from a fully-configured hacker box, so the usual network services would be working (sshd, VNC / Apple Remote Desktop, AFP, etc.) if OS X had come up OK, albeit without the internal display.

CLI login via ssh worked fine. Looking at the running processes, everything looked pretty regular... even VMWare daemons had started up successfully (even though the CPU it depended on had suddenly changed from a C2D to an i5 between reboots).

Next step - use Screen Sharing (already set up on the Air's SSD) - and miraculously, it worked. I got a 1280x1024 window (not the Air's display resolution, interestingly) displaying the old machine's LoginWindow. Even though the underlying machine had changed, my Server still offered it network logins, showing that it was both still accepted in the directory AND that the Snow Leopard build was playing nicely with the new hardware (it seems that you need *everything* working perfectly before Kerberos will join in).

Logging showed no problems other than the obvious fact that the system's original caches suddenly found that the hardware had changed underneath them... and that the display kexts hadn't been loaded because no nVidia chipset could be found. Everything *seems* to work apart from the display. This is fairly critical, but surely all this requires is the appropriate Intel integrated graphics kext, and a kext cache rebuild?

Anyway, that's how far I've got right now. I'm just re-installing the Snow Leopard 10.6.8 combo update (which will hopefully ensure the Intel drivers are included and then force a kext cache rebuild). Usually such updates require two reboots - one after install of new critical kexts (with no kext cache, so the required kexts (in my case, the Intel integrated graphics) are loaded on demand), and again once the on-demand kexts are loaded and a new kext cache is built.

So far, I'd disagree with the gurus here who dismiss the possibility of running Snow Leopard on the AirBooks that were shipped with Lion. It's almost certainly rather difficult to emulate my approach unless one has a spare small-form-factor SSD stick with a complete Snow Leopard system already installed - but I do, and the Air4,1 seems to be running Snow Leopard without any problems..... apart from an inoperative display 😀

If everything else in the system works... and my reapplication of the Combo Updater doesn't enable the laptop screen... surely all that's needed to get *everything* running is an appropriate set of graphics kexts for the Intel integrated GPU? Or even a simple edit to the appropriate kext to include the PCI IDs?

After all, I've got a PC Radeon HD5770 (native) and a PC Radeon HD6870 (with EFI flash hack) installed in my Mac Pro (dual Xeon MacPro3,1) - and whilst the 6870 needed kexts pulled from Lion, it's been stable ever since regardless of what's thrown at it. If the Air4,1 integrated Intel graphics also require Lion kexts, then it's no big deal. The important thing is that the system didn't panic...

Apologies for long post. Will follow up in a few minutes - the Combo Updater has finished...

Right then... it works.

The Snow Leopard combo updater isn't enough, since the machine profile MacBookAir4,1 isn't present in the IOPlatformPluginFamily.kext - and the Intel HD Graphics kexts are rumoured to need updating to Lion spec.

Rather than work through all the possibilities, I simply downloaded one of the Lion combo updater packs and extracted the MacBookAir4_1.plist platform plugin file (this tells OS X how to control the CPU's thermal states... essential with a Macbook Air - you may get the system running without it, or by using a .plist from one of the Macbook Pros, but I *really* don't advise it. Get the original file for the hardware you're running), along with two graphics kexts - the AppleIntelHDGraphics.kext and AppleIntelSNBGraphicsFB.kext (you want the 1.6.42 versions for the GPU kexts). I used Pacifist to extract the two kexts and the platform plugin .plist, but any tool that can extract files from the flat .pkg files used by Apple for combo updates will do.

Log in as root using ssh or screen sharing (which works even without the internal screen working), move the old kexts to a safe place (I simply renamed them to whatever.kext.OLD using mv from the CLI), and copy (cp -R) the kexts into S/L/E. Check that the files and subfiles are owned by root/wheel. Similarly, go into the IOPlatformPluginFamily.kext, navigate down through ACPI_SMC_PlatformPlugin.kext and into the folder containing the machine specifications. In a normal Snow Leopard install, you should see that there is no model newer than 3,1 in the MacBookAir .plists - copy in the MacBookAir4_1.plist file from the Lion updater. Ensure the owner and group are correct.

For good measure, I then rebuilt all the kext caches, using kextcache run as root twice with the -system-prelinked-kernel and -system-caches flags. Then rebooted.

First time round, it was a bit odd, with the framebuffer retaining the console output (I'd rebooted holding command-V) but displaying the mouse cursor. Using Screen Sharing from another machine, any mouse activity revealed the Login Window graphics on the internal screen 🙂 Very weird, and once I'd logged in, the proper output was displayed on the internal screen.

Translucent menu bar was present, so QE/CI work. Further testing and examination of console logs show that the OS knows that the machine is a MacBookAir4,1 and is operating the SandyBridge CPU properly.

Activity Monitor shows four virtual cores 🙂 so the two hyperthreaded i5 cores are understood properly (you almost *certainly* need 10.6.8 for this - the SB support in the kernel isn't there in earlier Snow Leopard versions).

So far, it appears to be 100% OK. Yes, it has a non-standard SSD (which is faster), but everything else works. And if you're upgrading (i.e. you have two 11" Macbook Airs at one point) then you can follow this procedure - update and patch the Snow Leopard system on the old Air fully to 10.6.8, enable Screen Sharing and Remote Login from anywhere, do a full backup, then take out the SSD and put in the SSD from the i5 Air, then boot from external DVD and restore the full 10.6.8 backup onto the new machine's SSD. When complete, don't reboot with the SSD inside - take it back out, put in back into the 4,1 Macbook Air, and let *that* reboot with the restored 10.6.8 system. The screen won't work, but as long as you've got a second machine that can Screen Share or ssh in, you can patch the graphics kexts and add in the Platform Plugin.

This may sound a bit intimidating for a unix newbie, but that's more due to the speed at which I'm describing this, being comfortable with the CLI myself. What this is doing isn't 'hacking the system to bits' - we're adding the machine CPU parameters from Apple's own description of the hardware, and updating two graphics kexts. I'm not 100% sure that the updated graphics kexts are, in fact, necessary... maybe just telling the kernel what the machine actually *is* (by including the platform plugin .plist) would make it work. But it's no big deal to add the Apple kexts (they're not modified - just pulled from Apple's own updates).

And since the files are taken from a Lion combo update, there should be no licensing or legal problems here. The MacbookAir4,1 is supplied with Lion, so you have a Lion license. Using files from that system (you could probably extract the required Platform Plugin .plist and two kexts from the original MacbookAir4,1 SSD as supplied by Apple, though it'd be more tricky) shouldn't be dodgy in the slightest, as I haven't modified the files in any way.

Obviously you need the Snow Leopard licence, and I can't think of many ways to do this without opening up the machine, so you'll need a Pentalobe screwdriver.

However, it is *definitely* possible to run Snow Leopard 10.6.8 on the MacBookAir4,1 without losing sleep, thermal states, or fan control. My machine has been running perfectly since I posted the previous instructions. It helps to use a known USB ethernet adapter for the net connection, just in case you're running internal DNS / DHCP - you want the new machine to get the same name / IP address as the old one if you're using the old one's system SSD. Apart from that, good news - you don't have to run Lion (apart from two of its kexts).

😀

Good news that you have achieved the "impossible"... Now is there any chance you can provide instructions for those of us without a previous MacBook Air?

I just (yesterday) received my brand new July 2011 MacBook Air (and chose it specifically because of the possibility of getting Snow Leopard to run on it) and have had limited success getting 10.6.8 to run on it. Sure, it works... But the function keys seem screwed up (I cannot adjust volume or backlighting) and no sleep function at the least. I also have an OWC SSD which I tried setting up via USB on my MacBook Pro. I am not familiar with the Terminal CLI and while I was able to stumble through a bit, could not figure out how to "go into the IOPlatformPluginFamily.kext, navigate down through ACPI_SMC_PlatformPlugin.kext and into the folder containing the machine specifications".

I was able to "install" the .plist and .kext files you indicated via Pacifist (using the install to other disk option), but it is clear there is a problem. I am going to give this another shot, hopefully with better results.

Any additional thoughts or advice is appreciated.

Hi Spif,

you have stumbled into the very reasons for not downgrading to a system that was never designed to support the hardware bundled in later computers.

I mean no offense to you, and offer kudos to your willingness to give it a try, even with a lack of familiarity with the Command Line Interface.

although I'm not familiar with the details of this thread, I've written a procedure for downgrading to Mac OS X 10.6.8 on several other computer models (MacBook Pro, Mac Pro). In that thread, I stated that the reasons for not applying that procedure to the MacBook Air, iMac, and Mac Mini were primarily that Apple had already put new hardware in these models, the drivers for which were not included in Mac OS X 10.6.8 (since this hardware didin't exist in computers built prior to the release of Lion).

as I recall from scanning other threads at the time, specific to the Mac Mini and MacBook Air, the issues you have with function keys and sleep were what others were experiencing. I can only imagine, from reading your post here, that this thread details how to pull a kernel extension system file from a "current" system, that does support the upgraded hardware in your Lion-delivered computer, and how to install those kernel extension(s) into the Snow Leopard OS.

This is part of what the Apple OS engineers do as they build an update to a current system. Doing so requires mucking around with the system that will run your computer - never a good idea without a solid backup or two so that you can restore to a working system if needed.

The other part that compilcates such a procedure for the MacBook Air is the lack of a firewire port. This removes the ability to boot from an external disk, which greatly simplifies such procedures for other computer models.

I know I haven't provided you with any "help" here - I do want to congratulate you, and encourage you to keep at it, and be prepared to run through this process several times, learning more as you go!

good luck to you,

Roy

You might be able to use rEFIit to boot to snow leopard. I just installed it on my new macbook air and it worked great. I am using it to run linux, but I think it would support a legacy OS X.

I have been trying to get it done these days and I have some encouraging results.

What I did : I used an external USB drive, on which I installed Snow Leopard 10.6 through an old MacBook Pro (2009). Then I made all the software updates, bringing it to 10.6.8 v1.1.

When booting the drive onto the MBA, I got only a black screen, so I put it back on the MBP and made the 3 .kext mentionned by Lex :

- copy the MacBookAir4_1.plist fond in the IOPlatformPluginFamily.kext of Lion's Extensions folder ;

- copy the AppleIntelHDGraphics.kext and AppleIntelSNBGraphicsFB.kext from Lion's Extensions folder

These copies should not be done using the Finder, because the permissions get messed up in the process, so here are some tricks to avoid this :

- use a software like Kext Wizard which allows to copy .kext from anywhere to the Extensions folder of the drive you want -- remember to execute the 2 last maintenance steps (repair & rebuild) in the "Maintenance" part before quitting ;

- restart Finder in root mode (very un-wise, considering the risks of breaking your currently running system)

- use Terminal with sudo commands like this (replace "DISK_WITH_LION" and "DISK_WITH_SNOW" with your respective volumes) :

1) Copies :

sudo cp /Volumes/DISK_WITH_LION/System/Library/Extensions/IOPlatformPluginFamily.kext/C ontents/PlugIns/ACPI_SMC_PlatformPlugin.kext/Contents/Resources/MacBookAir4_1.pl ist /Volumes/DISK_WITH_SNOW/System/Library/Extensions/IOPlatformPluginFamily.kext/C ontents/PlugIns/ACPI_SMC_PlatformPlugin.kext/Contents/Resources/

sudo cp /Volumes/DISK_WITH_LION/System/Library/Extensions/AppleIntelHDGraphics.kext /Volumes/DISK_WITH_SNOW/System/Library/Extensions/

sudo cp /Volumes/DISK_WITH_LION/System/Library/Extensions/AppleIntelSNBGraphicsFB.kext /Volumes/DISK_WITH_SNOW/System/Library/Extensions/

2) Permissions :

chmod -R 755 /Volumes/DISK_WITH_SNOW/System/Library/Extensions/IOPlatformPluginFamily.kext/C ontents/PlugIns/ACPI_SMC_PlatformPlugin.kext/Contents/Resources/MacBookAir4_1.pl ist /Volumes/DISK_WITH_SNOW/System/Library/Extensions/AppleIntelHDGraphics.kext /Volumes/DISK_WITH_SNOW/System/Library/Extensions/AppleIntelSNBGraphicsFB.kext

chown -R root:wheel /Volumes/DISK_WITH_SNOW/System/Library/Extensions/IOPlatformPluginFamily.kext/C ontents/PlugIns/ACPI_SMC_PlatformPlugin.kext/Contents/Resources/MacBookAir4_1.pl ist /Volumes/DISK_WITH_SNOW/System/Library/Extensions/AppleIntelHDGraphics.kext /Volumes/DISK_WITH_SNOW/System/Library/Extensions/AppleIntelSNBGraphicsFB.kext

All right, then do a full permission repair if you can (sometimes Disk Utility refuses to do it on external drive...) and boot on the disk with SL (hold ALT after boot chime and select it).

At this point, I landed on a functionnal SL with graphics acceleration but some video artifacts on screen : some lines seem not to change from the gray boot screen, but this can be wiped out by drawing a big rectangle on your desktop (as if you wanted to select all icons on it).

From there, I cannot manage to get a working trackpad & keyboard : the trackpad is behaving just like a single-button mouse (no multitouch whatsoever) and the special keys of the keyboard are all messed-up. I have tried to copy some other .kext from Lion (AppleHIDKeyboard.kext, AppleMultitouchDriver.kext or AppleUSBMultitouch.kext, for instance), without success : now I can change settings for the trackpad in System Preferences, but they do nothing at all.

I am pretty sure that these 2 problems can be solved, which could lead us to a real Snow Leopard downgrade for the mid-2011 MBA, because everything else (Sound, networking, sleep, apps...) works fine ! But Mutlitouch Trackpad is too much of a loss to justify quitting Lion yet in my opinion.

Hope somebody will manage to find a way !

For a long time I searched for a solution and I arrived at the same stage as you

Later I found your post 🙂

Have you found something new to the artifact boot and the trackpad?

Nope, sorry, still no progress. I have tried several others kexts, but it is just as if the trackpad&keyboard were hardcoded to the Lion kernel. Maybe it's a stupid idea, but I cannot understand why the driver is loaded but the devices doesn't seem to notice...

As for the video artifact, it is not so bad : just drawing a rectangle on the desktop when booting or waking the device is not so painful, and I guess this can be corrected with a parameter in the driver (frame-buffer, maybe ?). Honnestly, my main concern is the trackpad, then the keyboard, then the CGU.

Same thoughts as you, I continue to look...