A Messy Transition: Practical Problems With 32bit Addressing In Windows
by Ryan Smith on July 12, 2007 12:00 PM EST- Posted in
- Software
Other Problems, Other Solutions
Although for this article we are focusing on Supreme Commander, there are other games and applications that are already known to encounter this exact problem. Company of Heroes developer Relic has warned that this problem can occur, especially in conjunction with using Direct3D 10 mode and STALKER developer GSC Game World has also seen this problem. Both have gone so far as to ship the latest versions of their games with the LARGEADDRESSAWARE flag.
Although not an exhaustive list, we have compiled a list of recent games and applications and if they are flagged or not. Ideally every possible game and application that can run in to the 2GB barrier will be flagged so that it can be worked around without modifying the application directly itself.
| Large Address Aware Status | |
| STALKER: Shadow of Chernobyl | Yes |
| Lost Planet | No |
| Company of Heroes | Yes |
| Supreme Commander | No |
| Enemy Territory: Quake Wars | Yes |
| Battlefield 2142 | No |
| Call of Juarez DX10 BM | No |
| World of Warcraft | No |
| The Elder Scrolls IV: Oblivion | No |
| Photoshop CS3 | Yes |
| Dreamweaver CS3 | No |
| . | |
The importance of the above applications and games being flagged is not just to avoid the need to modify the executable, but also because there is another solution to the issue we haven't talked about so far. 64bit versions of Windows(i.e. XP and Vista) do not suffer from the traditional 2GB barrier, as all the kernel mode addressing is usually moved to well above the confines of the limited 32bit addressing area. As such, these versions of Windows don't need to have their space allocations adjusted for an application to gain access to more addressing space, bypassing the instability and any possible performance problems that occurs as a result of making this adjustment.
However in order to maintain compatibility with older applications, Windows still keeps the artificial 2GB barrier in place to keep from triggering any bugs that result from the extra space. So even if we use a 64bit version of Windows, the offending application must still either be flagged by the developer or modified by the user if we want to get past the 2GB barrier.
This in turn is an interesting proposition for developers who may be looking at ways to deal with the 2GB barrier, but don't want to make the jump to having to program and support 2 versions of their executables and associated compiled code. Although as a 32bit application there is still the 4GB hard limit, flagging executables lets a developer keep a single package and is perfectly safe on both stock 32bit and 64bit installations of Windows. They can effectively buy another 2 years or so before they need to actually offer 64bit executables, and can direct users to install a 64bit version of Windows if they are hitting the 2GB barrier, instead of directing them to make the much riskier user space modification.
Of course this is not all roses. As we covered in our Vista performance guide, there are still some issues with Windows Vista 64bit, and Windows XP 64bit is even worse as a result of having been orphaned quickly after its release. For prospective 64bit Vista users, they will still find that driver support is not as good as with the 32bit version of Vista, and 64bit drivers may not be as stable as the 32bit versions. There are also still lingering concerns over application compatibility and performance.
Things have gotten better since we published our February article, but we're not ready to write them off completely yet. Users getting along with 32bit versions of Windows right now will find themselves in between a rock and a hard place as more applications and games start to hit the barrier - they'll either need to make the user space modification or switch to a 64bit version of Windows when neither of these is a perfect solution. This leaves the less imperfect but also less fun option of simply turning down the settings on any affected games. Lower settings result in lower user space usage and reduced chances of crashing, but in spite of the highest stability and compatibility offered by this option we suspect few users will actually opt for it.
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instant - Saturday, July 21, 2007 - link
Could the writer please detail what, exactly, is wrong with XP-64bit edition?Having run it since it was released and never had a problem with it, I would be interested in knowing what problems I should have experienced.
BUL - Tuesday, July 17, 2007 - link
A few things I've found about /3GB in XP...1) In terms of "consumer" OS's, XP Pro is the only one to support it. (XP Home and W2K Pro DO NOT!) Vista has a different method, outlined in the article.
2) If you change boot.ini, make sure you add a "3GB" boot option to your operating systems, not just change the one entry to /3GB. If a new driver gets installed that doesn't like /3GB, you could be left without the ability to change boot.ini back. (I can't find any info on whether /3GB affects Safe Mode, however safe mode may run in "3GB" mode!) So, unless you have the ability to WRITE to NTFS partitions outside of Windows, you may be stuck if you don't. See http://www.gehrytechnologies.com/catia/catia/catia...">http://www.gehrytechnologies.com/catia/catia/catia... for how to do it...
Now, personally, I feel that a limitation like memory shows the "men from the boys" in terms of programmers. Windows and "endless memory" has allowed for bloatware for far too long and allowed for sloppy, inefficient programming... Just think back how many games & other programs could run on an XT with 640KB of RAM because the programmers wrote highly efficient code. (Lotus 1-2-3 for DOS was written primarily in assembler; Quattro Pro could open even larger spreadsheets than 1-2-3 because it utilized pseudo-virtual memory).
Now we've come full-circle into the world of Windows, and some of these programs now have to become more efficient. That's what programmers are paid to do...
Anorax - Monday, July 16, 2007 - link
On some of the larger maps in AW2 the game will occasional crash to desktop and leave an error window saying it has exceeded the 2GB memory space. Not that helpful but at least it tells you why it crashed.the Chase - Sunday, July 15, 2007 - link
Thank you so much for this article. I had a post awhile back in the forums asking for help on why in Vista I couldn't even run PR for bf2 unless I turned down the texture setting to Medium.Never figured it out though people here did offer some good ideas for fixes. After reading this article I knew this is what was going on. I searched on the Net and found out how to use Visual Studio C++ to modify the Bf2 executable. Problem solved! (I have the 64 bit version of Vista).
And to think I was ready(thinkeng about anyway) going to buy another 2 GB's of memory to try and cure the problem. Thanks again.
P.S. I also did the same fix for XP pro 64 and now PR runs much smoother than before in that OS also.
spookware - Friday, July 13, 2007 - link
Just wanted to mention that the description of how windows uses memory is correct for XP and previous versions but it is not quite how windows vista works.Specifically, vista does not automatically take the upper 2GB of adress space for the kernel any more. It instead grows the kernel adress space downard on demand. Allthough the associated switches (/3G) have the same prupose in vista what they are setting is actually the upper maximum for the kernel adress space.
Magumi - Friday, July 13, 2007 - link
I guess this means that if I want to buy a computer to last me at least three or four years, I need to get 64bit Vista and 8GB of RAM and hope that drivers and incompatibilities get resolved soon.Greyhead - Friday, July 13, 2007 - link
Ryan, great article. Some other posters mentioned the use of the /PAE on servers. I recently discovered that MS recommends NOT using the /3GB switch in conjunction with /PAE. I followed their advice on a large SQL server we have and saw immediate positive results. The problem with /PAE /3GB combination is that when the OS is limited to 1 GB, there is not enough room for the size of the heap needed to support the /PAE option! This can be viewed using performance monitor - selecting "memory" options and then viewing total PTEs available (Page Table Entries). There are MS articles that describe the minimum PTEs needed, and before I changed our server it was way under the minimum. We had stupid errors on the server - blue screens, "not enough memory" errors when transferring files to another machine. Once the change was made, these problems disappeared. 2003 server has a more tunable /3GB switch using the /USERVA switch. There are technet articles which provide guidance on it's usage.Keep up the great work -
-bill
redpriest_ - Friday, July 13, 2007 - link
binary is illegal.Kougar - Friday, July 13, 2007 - link
The moment I saw the title I was thinking of Supreme Commander. I particularly enjoy the insanely huge 8-player games, but it only took about 40 minutes before these would crash... oddly enough they did not always crash either in some situations, making the crashing appear random and only confusing my attempts to troubleshoot this game. It would have been quite appreciated that this issue would have at least been mentioned in the game's readme file, if nothing else.Having (very luckily) stumbled across MadBorris's thread I made the modifications to XP and SC has been running since. I have not run into any instability or issues with XP configured with the /3gb switch for what it is worth. Am I wrong in that users with video cards featuring smaller onboard memory sizes will have an "advantage" with this problem? There is a large difference between a 320mb GTS and 740MB GTX, or heaven forbid a 1GB HD 2900 card? And while on the subject does a dual-GPU configuration (and therefore dual VGA memory) make things even worse?
Ryan Smith - Friday, July 13, 2007 - link
Yes to the first question. To the second question I believe that's also a yes, but I don't have a system configured to test that theory.