Lion is the first OS X release to drop support for any Intel processors – machines using 32-bit Core Solo and Core Duo machines (sold mostly in 2006 at the very beginning of the Intel switch) aren’t able to install the new OS without hacking (which is outside the scope of this review). This is common practice for Apple, whom habitually irks a small but vocal portion of its userbase who insist (not altogether unreasonably) that their Macs are still running just fine.

Apple usually doesn’t do this lightly – in most cases, dropping support for older models is done to move the platform forward (though, as when 10.4 dropped support for Macs without FireWire, it can also be done to push particular proprietary technology). Just as Snow Leopard pulled support for PowerPC Macs to emphasize Intel development, Lion will pull support for x86 to push 64-bit development.

I’ve seen quite a bit of confusion on this topic (and there was quite a bit when Snow Leopard trumpeted full 64-bit support at its release), so I want to go into some detail about the history of 64-bit OS X. If you’re not interested in that, though, let me lay out the most important stuff in brief:

  • Core Solo and Core Duo-equipped Macs are the only Intel Macs being dropped by Lion. Even if it can’t boot the 64-bit kernel of Lion or support 64-bit EFI, any Mac that came with a Core 2 Duo (or any 64-bit capable Intel processor) can install and run Lion without modification.
  • Core 2 Duo-equipped Macs that don’t support OS X’s 64-bit kernel or 64-bit EFI can still run 64-bit apps, which can address more than 4GB of RAM.
  • The Lion installer isn’t actually doing checks for processor capability, but for your Mac’s model identifier, meaning that Core Solo and Core Duo Mac Minis and iMacs that were later upgraded to Core 2 Duo processors will still fail to install Lion without modification because the installer assumes they’ll be running 32-bit processors (though if you can get Lion running, your processor should be able to run everything just fine). Remember that these processor upgrades, while technically possible, were never supported by Apple.

Now for a history lesson, combined with about as much information about Lion’s 64-bit support as you could ever want.

64-bit in Mac OS X 

OS X’s 64-bit implementation differs significantly from that of Windows, which treats its 32-bit and 64-bit versions as two distinct operating systems stored on different install media. This is done mostly to maintain Windows’ compatibility with older applications – moving or renaming things like the System32 folder would break programs that expected it to be there – and as a result the two are separated to the point that there isn’t even an upgrade path between 32-bit Windows and 64-bit Windows. Because of this, and because Windows applications and drivers usually have distinct 32-bit and 64-bit versions, Windows’ transition to 64-bit has been slightly rockier and slightly more visible to the user.

OS X, on the other hand, has made a more gradual transition between 32-bit and 64-bit, with support added slowly over the course of multiple releases. OS X 10.3 and 10.4 came with some basic support for 64-bit underpinnings, but support for 64-bit applications didn’t come until 10.5 Leopard (which included the 64-bit version of Cocoa, OS X’s primary API). The same technology that allowed developers to offer Intel and PowerPC programs as a single Universal Binary also allows developers to release single packages that support both the x86 and x64 architectures.

While Leopard brought support for 64-bit apps that can address more than 4GB of memory, Snow Leopard actually introduced an OS kernel (along with 64-bit kernel extensions and drivers) that was 64-bit, though a 32-bit kernel was used by default on almost all Macs whether they supported the 64-bit kernel or not. This was done mostly to give software developers time to get 64-bit KEXTs and drivers ready – since Snow Leopard’s release, Apple has released both Mac Pros and MacBook Pros that boot with the 64-bit kernel by default (and OS X Server uses a 64-bit kernel by default in even more models, as outlined in this Apple support document).

Lion pushes this a bit further by booting a 64-bit kernel on basically any Mac that supports it – the 2007 aluminum iMac, the 2009 unibody MacBook Pro, and the 2010 MacBook Air I used booted Snow Leopard with the 32-bit kernel by default, but booted with the 64-bit kernel for Lion (and the iMac and the Air didn't even support the 64-bit kernel in Snow Leopard). That being said, Lion still includes the 32-bit OS X kernel, and will use it on machines that don’t support the 64-bit kernel – you can still make full use of 64-bit apps and more than 4GB of RAM, even though the OS kernel itself can’t. This won't usually be a big deal, since the Macs that can’t use the 64-bit kernel are mostly older models with RAM caps at or under 4GB anyway.

In both Snow Leopard and Lion, you can check your kernel's 64-bitness by opening up System Profiler/Information, going to the Software section, and looking at the "64-bit Kernel and Extensions" field. Yes means a 64-bit kernel, No means 32-bit.

Lion with a 32-bit kernel on a 2008 MacBook

Support for the 64-bit kernel requires four things to be true: You need (obviously) a 64-bit Intel processor, a Mac that supports 64-bit EFI, hardware for which OS X has 64-bit drivers (graphics cards are usually the problematic area here), and a Mac that has not been specifically disallowed from booting the 64-bit kernel – most new Macs support the 64-bit kernel, but white MacBooks are still artificially limited by Apple from booting the 64-bit kernel in Snow Leopard despite hardware that fully supports it. Most if not all of these artificial limitations have been removed in Lion for machines that meet the other 64-bit criteria.

Apple began really pushing 64-bit with its marketing for Snow Leopard, and has been dropping support for 32-bit APIs like Carbon for years – giving developers aiming for Lion guaranteed 64-bit capability both enables them to better take advantage of the architecture improvements and saves them the effort (and file size) of also supporting a 32-bit version. That said, 32-bit programs will continue to run fine in Lion, just as they ran fine in Snow Leopard and Leopard before it.

The hidden downside of the 64-bit push for Core Solo and Core Duo users is that, as developers slowly move to 64-bit only applications, we’ll start getting more and more things that won’t run on 32-bit Snow Leopard despite being supported on 64-bit Snow Leopard (the same thing is currently happening to Leopard users still using PowerPC processors – Flash Player, Google Chrome, Firefox 4, and Microsoft Office 2011 are all fairly mainstream apps that run in Leopard but only on Intel machines). The disappearance of 32-bit programs will be gradual, but it is something to be wary of if you continue to use a Core Solo or Core Duo Mac going forward.

What gets dropped next?

This discussion isn’t complete without a look into our murky crystal ball to see what Macs will be dropped by the next version of Mac OS. The continued push for 64-bit makes me think that we could see machines incapable of running the 64-bit kernel dropped, though that line in the sand could be too faint for most consumers to see, especially given the scarce and not-always-clear documentation on what Macs support it in the first place.

It’s worth noting that Apple could easily issue EFI, KEXT, and driver updates for any Macs it wants to enable to run the 64-bit kernel – there are some models like the 2007 aluminum iMac (iMac 7,1, for those who prefer information pulled from System Profiler) that didn’t support Snow Leopard’s 64-bit kernel, but boot with Lion’s 64-bit kernel by default.

The more likely cutoff point for 10.8 (or OS XI, or whatever comes next) is graphics-related – Apple has been shipping mostly OpenCL-capable products since 2009, and by the time the next Mac OS is upon us (2013-ish, at the current rate), products pre-dating OpenCL support will mostly be four and five years old (roughly the same age as the current Core Solo/Duo Macs). If Apple continues its trend of dropping products that hold back the platform in one way or another, pre-OpenCL machines seem to be the most likely candidates on the chopping block.

Screen Sharing, Boot Camp, Migration Assistant SMB File Sharing in Lion
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  • mrcaffeinex - Wednesday, July 20, 2011 - link

    I purchased a MacBook Pro when Leopard was due to come out. Apple mailed me a free upgrade DVD about a month after I purchased the MacBook. When Snow Leopard came out I purchased the upgrade DVD for something in the neighborhood of $30 if I remember correctly. I've done clean installations from all of the media and never run into an activation/registration problem.

    On the flip side, I paid $149 for Windows XP, another $149 for XP 64-bit (if only there had been driver support back in the day...), $199 for Vista and another $149 for 7. Granted these were over a slightly longer time period. Still, I can't help but think that some of the initial investment cost of the Mac has been offset by not having to spend significantly more on software upgrades to get the features or functionality that I enjoy having at my disposal.

    Factor in the inconvenience of having several iterations of Windows that were more or less junk, but still cost the same and it slides the scale further in favor of OS X in my experience. Now I can also get what is essentially a household upgrade in Lion for approximately $30 if I decide it is worthwhile.

    Don't take this as an attack on Microsoft and their Windows operating system, though. It is still an integral part of my computing experience every day and I really enjoy Windows 7 (in fact, it runs better on my MacBook than on most notebooks I've worked on). I just wish they would adopt a strategy that would make upgrading Windows more affordable for the do-it-yourself PC enthusiast.
    Reply
  • GotThumbs - Wednesday, July 20, 2011 - link

    The amount of money Apple made on your purchase of their hardware more than covers the cost of the OS. Microsoft does not sell their own brand of computers. You can purchase a PC laptop for hundreds less than you can purhcase an Apple MAC.

    Think McFly, think!
    Reply
  • xype - Thursday, July 21, 2011 - link

    I love it how PC people have such a sweet feeling of entitlement.

    Have you ever had/bought/found a product that you were simply content with paying a premium for because it just worked well for you? Have you ever overtipped a waiter because the service was really good?

    You know, some people don’t have a problem rewarding either individuals or, yes, teh ebil corburayshns, for work/services well done.
    Reply
  • GotThumbs - Thursday, July 21, 2011 - link

    ??? "feeling of entitlement" ???

    Not sure what you mean, but I do work hard for my money and do have a choice of where I spend it and how much I'm willing to pay for a product or service. There is a HUGE difference between tipping a waiter for working hard to provide you the best experience, than a company who sells consumers the same technology I can get elsewhere for less and be just as satisfied with my purchase. I'm not a 'Scrooge', but I'm also not a fool. Meaning: A fool and his money are quickly parted.

    I build my own systems so I not just satisfied with what is put out by the large PC sellers either. Most readers here are not satisfied with being 'spoon fed' what we should be satisfied with.

    If you or anyone else wish to purchase apple products, your free to do so. Just don't expect me to give you a pat on the back for it.
    Reply
  • steven75 - Friday, July 22, 2011 - link

    You seem to have missed the entire point that Microsoft OS upgrades are *hundreds of dollars* per copy and Mac OSX upgrades are $30 for multiple copies. Reply
  • wicko - Sunday, July 24, 2011 - link

    Umm, currently it is roughly 100$ for Home Premium (I paid 125 when I preordered Win7 Pro Upgrade edition), less at some retailers.

    Not to mention, you glossed over the fact that there does exist a "mac tax", which you would have paid on every mac you own, offsetting the total cost.

    Say I spend 2400 on 3 PCs (including OS) and you spend 3000 on 3 Macs. Performance is identical. It will cost me 300 to upgrade each one to Win7. It will cost you 30$ to upgrade all of your Macs. 2700 vs 3030, Interesting. I will have to go through another version of Win7 in order to catch up with you in cost. And I'm being generous with respect to the difference in price before upgrades.

    But, you know, you can install it on as many Macs as you'd like, so go nuts. Just don't pretend you're somehow spending less than those who buy Windows licenses.
    Reply
  • anactoraaron - Sunday, July 24, 2011 - link

    Sure, but let's compare apples to apples (pun intended). If Microsoft were to charge $150 for what little differences there are from 10.6 and 10.6 + hybrid iOS called 10.7 windows discs would never sell (who the hell buys MS discs retail that reads AT anyway?? Newegg has always sold oem discs MUCH cheaper-wait apple person NM). But to sit there and tell me that there isn't any major changes from XP to 7... that's just ridiculous. Reply
  • xyn081s - Monday, August 1, 2011 - link

    I think you're the one who missed the point. Even with all these Win licenses, it'll still be cheaper than a Mac. Plus, you can get the Family pack, 3 licenses for $150... Reply
  • ex2bot - Friday, August 5, 2011 - link

    I know this comment was a few days ago, but I had a laugh at your comment, so I just had to open my digital mouth and reply:

    "2400 for 3 PCS ($800 ea.) and $3000 for your [POS] Mac".

    If you paid $40,000 for three Chevy Malibus and I paid $80,000 for my one souped-up Corvette" I would have gotten RIPPED OFF! (No, actually I would have received A LOT OF TICKETS!!)

    A better comparison is

    $800 PC vs. $1400 iMac . Not 800 vs. 3000. * Incidentally, you can sell your used Mac for a lot more than the technically equiv. PC. I've used that to upgrade my Macs several times.

    -Ex2bot
    Mac Fanbot

    * Think an $800 PC = Mac Pro? The Mac Pros have Xeon processors. You know better than I that Xeons are $400 or $500 each. The cheapest Mac Pro has *dual* E5620s @ 2.66. You can't build a octo-core Xeon machine for $800. And you've got to have a motherboard and a, what, case? Power supply? And a few other parts, right?
    Reply
  • nafhan - Wednesday, July 20, 2011 - link

    So, you bought four copies of Windows for a single computer? You may be the only person to have done this... A more typical experience over that time period is: Windows XP "free" with new PC, and $100 to upgrade to Windows 7.

    With the amount of money you spent on OS licenses, you could have purchased both a Win XP computer (OS included) and a Windows 7 box (OS included) outright.
    Reply

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