Newest KB Articles in FSX General

VAS management - stopping out of memory (OOM) errors

Sat, 22 Mar 2014 19:23:50 GMT

(This article originally appears in the PMDG 777-200LR/F Introduction manual on pages 21-25)

We would like to acknowledge FSX community member Srdan “Kosta” Kostic’s research into the OOM problem and VAS usage on which a good portion of this article is based.

Background and theory:

FSX is a 32-bit application. Even under the recommended Windows 7 64-bit operating system, the FSX.exe process always faces the same mathematical limitations that all 32-bit applications do. One of these is a 4GB hard limit on something called “virtual address space” (VAS). When FSX crashes with an error message saying that your computer has run out of available memory (commonly called an “OOM” in the sim community), it’s actually talking about VAS, not physical memory like the amount of RAM in your system. Customers who have huge amounts of RAM like 16GB or 32GB are often baffled by this message for good reason – they certainly aren’t running out of physical memory. Microsoft probably should have made the error say “The application has run out of virtual address space.” instead of the vague “memory” term.

VAS is effectively a preallocation of everything the simulator can potentially access during a flight and will fluctuate over the course of using the simulator as you fly between different areas. Note that VAS is *NOT* the same thing as the “virtual memory” swapfile that you can set the size of in the Windows system options – they are two very different things and having a large virtual memory swapfile does not protect you from the 4GB VAS limit. The mathematical limit itself comes from the definition of “32-bit” – a bit is the most basic data structure in computer science and it can have two values, a 0 or 1, which can mean all sorts of things like true or false, on or off etc. This is why at the core a computer executes “binary” code. The amount of VAS a 32-bit process can access can be calculated by raising the number of possible values for each bit (2) to the power of the number of bits available (32). So 2^32 equals exactly 4,294,967,296 bytes (not bits). When you do the rest of the conversion math this value comes out to exactly 4 gigabytes of potentially addressable memory for a 32-bit process.

The reason we recommend using a 64-bit operating system like Windows 7 64-bit is due to the fact that it can give FSX.exe that entire 4GB block of VAS. In 32-bit Windows the default is a maximum of 2GB of VAS for FSX and 2GB reserved for the operating system. This can be increased to 3GB for FSX through an edit to the boot environment configuration (“the 3GB switch”), but this is still 1GB lower than you’ll get with the 64-bit version of Windows and it makes both OOMs more likely and OS crashes more likely because it reduces the amount of VAS the OS itself has to work with. 32-bit versions of Windows can also only ever access 4GB of total physical memory, so if FSX is using 3GB itself, there’s not much there for the OS and other applications. 64-bit Windows does not have this limit and with a lot of RAM you can essentially run as many other applications outside of FSX (browser, weather apps, flight planners etc) as you want with no effect on the system. There is literally no reason not to run the 64-bit version of Windows 7 on an FSX simming PC.

If you’d like to read more in depth about VAS and the other types of memory used in Windows, Mark Russinovich’s blog has an excellent series of articles that detail it:
http://blogs.technet.com/b/markrussinovich/archive/2008/11/17/3155406.aspx

Mark is the author of the Process Explorer tool below, a member of the Windows kernel design team at Microsoft, and one of the most knowledgeable people in the world on how Windows actually works.

Using Process Explorer to monitor VAS:

With the proliferation of so many high detail aircraft and sceneries for FSX in recent years, the sim can easily approach and in many cases exceed the 4GB VAS limit. As the sim approaches the limit, very odd things startcan start happening like disappearing scenery, disappearing or transparent visual models on the aircraft, flashing artifacts, long pauses and so on. If it exceeds the limit you will get the OOM error window or the sim will just crash to desktop (CTD) without any error message at all.

If you’re having VAS issues, the first step is going to be to determine how much VAS FSX.exe is actually using throughout your flight. Fortunately Microsoft has a tool that allows you to do exactly this called Process Explorer – you can download it here:
http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

Once you have it downloaded, unzip the files to a folder of your choosing and run the procexp.exe file. You’re going to see a rather bewildering looking list of all the processes running on your computer with various columns full of parameter values that are constantly updating. The first thing you’re going to want to do is enable the VAS display – to do this, right click in the area where the column names are and choose “Select Columns”. Go to the “Process Memory” tab in the window that pops up and put a check mark next to the one called “Virtual Size” and press OK. This is going to enable the column, but it will likely be at the far right of the Process Explorer display. We recommend maximizing the window and then dragging the Virtual Size column over so that it’s right next to the CPU column so that you can easily see it. Click the top of the column where it says “Virtual Size” until you see a downward pointing arrow, which means the list is now sorted with the highest VAS using applications first in the list. You can now resize the window to a more manageable size.

Now run FSX and monitor this number for the FSX.exe process while you use the simulator. It should quickly move to the top of the Virtual Size column as the sim loads. If you see it start to get close to 4,194,304K (this is 4GB in kilobytes) – you know you have a VAS problem.

Causes of high VAS usage:

The PMDG 777-200LR/F aircraft itself uses approximately 700 to 800MB of VAS based on our testing, split roughly equally between the VC and external models and the aircraft systems programming. This is in line with other high-end addons aircraft on the market and is not excessive given the advanced capabilities of the product. Great care was taken to optimize and not increase the VAS load of the aircraft beyond what is necessary to simulate it properly.

Here are some of the more common causes of high VAS usage we’ve identified:

Large amounts of photoscenery areas
Products that install photoscenery for whole US states or whole European countries are a particularly high source of VAS usage when a lot of them are enabled at once. There are several such packages on the market and all of them will exhibit this issue. FSX unfortunately allocates VAS for these areas *even if you are not flying over them and never go near them*. We have observed almost instantaneous OOM errors upon loading our products on customer PCs where they had for instance the entire eastern United States photoscenery installed. Disabling the photoscenery reduced the total VAS load by well over 1GB and allowed the simulator to function normally. Users have reported success with photoscenery and our products by enabling only the states or countries their route passes over. Use Process Explorer to monitor VAS and see if this works for you.

To the best of our knowledge the reason this happens is because photoscenery uses a unique texture for every single area within it. Normal FSX scenery uses a small group of textures that get repeatedly used via the landclass system. Having to precache and allocate for the presence of that many textures is likely at the root of the problem.

Here is a link to a very good open source utility called SceneryConfigEditor that will allow you to make groups of scenery areas that you can turn on or off with a single click:
http://sourceforge.net/projects/fs-sceditor

High amounts of AI traffic

Be reasonable with the amount of traffic you’re putting into the simulator. Often the high 100%-type levels become unrealistic anyway from the fact that FSX’s ATC system bunches them up and can’t handle vectoring them all. You end up with a ton of go-arounds, a massive line for takeoff and so on. That many airplanes also eats into the VAS allocation. Again, this is not dependent on the specific traffic product you’re using.

Ultra high resolution environment textures
Many “environment” type addons (as with the photoscenery and traffic there are several of these available) contain options to install very high resolution textures for things like clouds, water, runways and taxiways and so on. It is our experience that these maximum resolution textures often increase the VAS load disproportionally to the amount of visual improvement they provide. A 4096x4096 resolution texture actually contains 16 times the amount of pixel data that a 1024 resolution version of the same texture does. The 1024 or 2048 versions of the textures you’re installing are likely going to be visually indistinguishable to you from the maximum 4096 version and they will result in both lower VAS usage and lower GPU memory usage.

FSX.cfg LOD_RADIUS value
Some tweak guides recommend increasing this setting in the FSX.cfg file above its normal 4.500000 maximum value. While this does improve visual detail into the distance, that improvement comes at the expense of increased VAS usage because FSX has to load in more autogen, more high detail mipmaps for textures etc. Leave this setting at 4.500000 unless you’re actively monitoring your VAS usage and are sure that setting it higher isn’t putting you into OOM territory.

Autogen, water, weather
The usual culprits for lowered performance in FSX also are the main drivers of VAS usage. Lowering them can significantly reduce the VAS load if you’ve exhausted the other possibilities.

High detail addon airports
While the effect of these in our testing is relatively minor, if you’re having problems with OOMs, you may want to consider disabling the ones you’re not actively flying between.

Flying a lot of legs without shutting the simulator down
The reason is not exactly clear, but FSX appears to not fully release the contents of scenery areas that have been used during the session. We have observed OOMs happen when flying around to a bunch of different high detail airports over high detail terrain all over a long period of time. To avoid this, simply save your flight after landing and shutdown, close FSX, and then reload it and your flight and you should be in a reset VAS
state.

Conclusion:

There are real limits in the 32-bit FSX environment that you have to be aware of and manage. It all comes down to deciding what’s most important to you. It is likely impossible for you to run every high-end aircraft and scenery addon all together at their maximum settings without making compromises to stop the OOM error from happening. It is up to you to decide what’s most important to you and prioritize between different addons using the tools outlined here.

dll.xml Information and Troubleshooting

Thu, 02 Dec 2010 01:38:35 GMT

DLL.XML INFORMATION AND TROUBLESHOOTING

Several addons corrupt the FSX dll.xml file, which can render inoperative any addon that relies on dlls loaded from it. Numerous attempts at getting these developers to fix this issue have gone unanswered.

At its most basic level with no actual addon dlls loading, the dll.xml file looks like this:

<?xml version="1.0" encoding="windows-1252"?>

<SimBase.Document Type="Launch" version="1,0">

<Descr>Launch</Descr>

<Filename>dll.xml</Filename>

<Disabled>False</Disabled>

<Launch.ManualLoad>False</Launch.ManualLoad>

</SimBase.Document>

Actual entries for loading dlls look like this and are placed after the Launch.ManualLoad tags but before the ending SimBase.Document tag in the basic structure shown above:

<Launch.Addon>

<Name>PMDG HUD Interface</Name>

<Disabled>False</Disabled>

<Path>PMDG\DLLs\PMDG_HUD_interface.dll</Path>

<DllStartName>module_init</DllStartName>

<DllStopName>module_deinit</DllStopName>

</Launch.Addon>

Most of a dll.xml is made of up a succession of these entries that tell the sim to load particular addon dlls.

HOW TO FIND YOUR DLL.XML

The dll.xml file is normally located in a hidden location. Here's how to find it.

First you need to open the Windows Folder Options. You can get to this either from Control Panel, or by going to Tools/Folder Options from any Explorer window that shows your drives and folders such as My Computer.
In the Folder Options, you need to change two options on the View tab away from their default settings:
1. The first is "Hidden files and folders" - you need to change this to the 2nd option down that says "Show hidden files, folders, and drives."
2. The second is "Hide extensions for known file types" - uncheck this option. Extensions are the second half a filename, for example .doc, .jpg, .mp3, or in this case .xml. For some reason, Microsoft decided to hide these by default, which can make it difficult to identify the exact files in a list.
Now, you need to browse your main C: drive, and go to one of these locations depending on whether you have Windows XP or Windows Vista/Windows 7:
- Windows Vista\Windows 7\Windows 10:
  C:\Users\(Your Windows Account Name)\AppData\Roaming\Microsoft\FSX

The dll.xml file is in this folder. (Note that this is also the location of another very important file - your fsx.cfg)

HOW TO FIX COMMON PROBLEMS WITH DLL.XML

Problem 1 - newline characters:

There are invisible formatting characters that make up what's called a "newline" in a text file. In Windows and a couple of other operating systems the newline sequence is "CR LF" - those stand for "carriage return" and "line feed" - they're terms that originated a long time ago with telegrams and mechanical typewriters. In Unix or Linux based operating systems however, the standard is just a single LF character. This is what happens with certain installers by other companies, they're stripping the CR characters out of each newline the file and making it the Unix/Linux format with just LF. Windows Notepad can't read Unix style newline formating, so you'll see just a string of text with no line breaks when you open one of these corrupted files with it.

Download a copy of Notepad++ here (which can read Unix/Linux text files) and you can actually see these characters and fix them:
http://notepad-plus-plus.org/download
In the program, go to View/Show Symbols/Show End of Line.
You'll now see a bunch of black and white boxed CR and LF characters at the end of each line in a good dll.xml file. If you see just LFs, the file's been corrupted.

To fix the LFs, you can do one of two things:

Go through manually, position the cursor before each LF and then press Ctrl+M, which inserts a Windows newline. (CR LF)
The much easier method is to go to Edit/EoL Conversion and Select Windows Format. If Windows is greyed out, select Unix Format first, and then move it back to Windows. It'll automatically convert all the LF to CR LF.

If that's the only thing that was wrong with the file, you're good to go and your addons should start working again because FSX can now read the file.

Problem 2 - truncated/orphaned pieces of entries:

Sometimes the file structure itself is corrupted and you'll see entries and lines out of order. For these, use the other entries as an example and attempt to place them in the proper format. If you are uncomfortable, or need additional help, you may

find some success in our customer forum located at forum.pmdg.com.

It is a very good idea to back up your dll.xml file before installing an addon, just to ensure that you have a good working copy to refer to in case the addon corrupts it.

How to uninstall and reinstall FSX

Fri, 26 Feb 2010 19:26:00 GMT

It certain scenarios, it can become necessary to reinstall FSX or FSX: Steam Edition. This article will take you through the process of fully uninstalling the sim, reinstalling it clean, and for FSX retail, getting it patched back up to SP2 or Acceleration.

THE UNINSTALL

WARNING - this will completely remove everything associated with FSX including your saved flights and fsx.cfg. Back these up if you'd like, but it is imperative that you start off completely clean to ensure such files weren't involved with your issue. Leaving them there through the reinstall could trigger the issue again if it is related to them.

Go to Add or Remove Programs under Windows XP or Programs and Features under Windows Vista through 10. Remove any addons you have installed for FSX, including aircraft, scenery, and utilities such as weather addons. You need to do this because many addons (like our own) feature validation protection or registry entries that will get reset when you uninstall, if you leave your addons there, they may fail to reinstall correctly later. You cannot just copy addon folders and then copy them back in later - this does not work for most due to things that need to happen during their installation to properly setup and validate them. If you have a side-by-side install of both FSX retail and FSX: Steam Edition, make sure you only uninstall the addons associated with the version of the sim you're trying to clean reinstall!

Double check the list and make sure you got all of them. You may also want to check the Start Menu Programs list and see if you have any addons remaining there as well which may only uninstall through a link in the menu.

Find the entry for FSX and uninstall it. This may say Acceleration, Service Pack 2, Steam Edition, etc. If you have a side-by-side install of both FSX retail and FSX: Steam Edition, make sure you only install the one that you're trying to reinstall! If you have FSX: Steam Edition, you can also uninstall it directly from your games library list within Steam.

Once it is done uninstalling, close the control panel and reopen it. It is likely you will now see FSX still present in the list. This is because the previous step only uninstalls the Acceleration pack or Service Pack. Uninstall whatever is now in the list for FSX. Keep going through this step until no FSX entry shows up after you reload the control panel. (this is not necessary for FSX: Steam Edition.

Open Windows Explorer and find your FSX root folder.

By default this is located at:

FSX retail edition:
32-bit versions of Windows: C:\Program Files\Microsoft Games\Microsoft Flight Simulator X
64-bit versions of Windows: C:\Program Files (x86)\Microsoft Games\Microsoft Flight Simulator X

FSX: Steam Edition
32-bit versions of Windows: C:\Program Files\Steam\steamapps\common\FSX
64-bit versions of Windows: C:\Program Files (x86)\Microsoft Games\Microsoft Flight Simulator X

Delete this folder (just the FSX one, not the entire tree), answering yes to any dialogs that pop up warning you about it. You don't want anything left over in this folder so that you start out completely clean for the reinstall.

Open Windows Explorer and find your FSX application data folder. By default this is located at:

For FSX retail or FSX: Steam Edition in stand-alone mode:
Windows XP: C:\Documents and Settings\(Your Windows Account Name)\Application Data\Microsoft\FSX
Windows Vista\Windows 7: C:\Users\(Your Windows Account Name)\AppData\Roaming\Microsoft\FSX

For FSX: Steam Edition in side-by-side mode:
Windows XP: C:\Documents and Settings\(Your Windows Account Name)\Application Data\Microsoft\FSX-SE
Windows Vista through 10: C:\Users\(Your Windows Account Name)\AppData\Roaming\Microsoft\FSX-SE

Delete this folder as before, being careful to only delete the FSX part, not the entire folder tree.
Open Windows Explorer and find your FSX shader cache folder. By default this is located at:

For FSX retail or FSX: Steam Edition in stand-alone mode:
Windows XP: C:\Documents and Settings\All Users\Application Data\Microsoft\FSX
Windows Vista through 10: C:\Users\(Your Windows Account Name)\AppData\Local\Microsoft\FSX

For FSX: Steam Edition in side-by-side mode:
Windows XP: C:\Documents and Settings\All Users\Application Data\Microsoft\FSX-SE
Windows Vista through 10: C:\Users\(Your Windows Account Name)\AppData\Local\Microsoft\FSX-SE

Delete this folder as before, being careful to only delete the FSX or FSX-SE part, not the entire folder tree.

Open Windows Explorer and find your FSX saved flights folder. By default this is located at:

For For FSX retail or FSX: Steam Edition in stand-alone mode:
Windows XP: C:\Documents and Settings\(Your Windows Account Name)\My Documents\Flight Simulator X Files
Windows Vista through 10: C:\Users\(Your Windows Account Name)\Documents\Flight Simulator X Files

For FSX: Steam Edition in side-by-side mode:
Windows XP: C:\Documents and Settings\(Your Windows Account Name)\My Documents\Flight Simulator X - Steam Edition Files
Windows Vista through 10: C:\Users\(Your Windows Account Name)\Documents\Flight Simulator X - Steam Edition Files

Delete this folder as before, being careful to only delete the FSX or FSX-SE part, not the entire folder tree.

The system is now clean of FSX.

THE REINSTALL

For retail FSX retail edition:

If you have the newer Gold Edition of FSX, it has everything you need already integrated. Install both FSX and Acceleration from its DVDs and you're good to go. If you have the older Standard or Deluxe Edition, follow the instructions below.

Install FSX from the DVDs. This will put you at the RTM (release to manufacturing) version - the original code Microsoft shipped with the game in 2006.

IMPORTANT - we do NOT recommended installing to the default file location in Windows Vista or Windows 7. (Program Files or Program Files (x86)) - Windows "protects" anything within these folders and has been shown to cause numerous problems with the install and configuration of addons. We recommend you pick a simple folder path outside of these folders such as C:\FSX

Run the sim once, going through the validation process and then loading it up to the point where you see the main interface. You do not need to load into the sim itself, load an aircraft or anything like that. The purpose of this step is to initialize the FSX.cfg file and a few other processes that get the sim ready to use. You will likely experience trouble if you try to go directly to installing the Service Packs or Acceleration without doing running the sim once first to initialize it.

Now you have a choice to make, if you own Acceleration, install that off the DVD, validate it, and you are done. It already includes everything that SP1 and SP2 do. Do not try to install either of the Service Packs after you've already installed FSX. If you do not have Acceleration, continue on to step 4.

Download SP1 here and SP2 here. You need both files. (note, Microsoft removed these files from their own server years ago, these are the correct files in a known good location)

Install SP1. Run the simulator once after, just as you did before with the RTM version.

Install SP2.

FSX is now installed clean and up to date. You can now set up your options and begin installing your addons. We recommend performing a defrag after you're done, preferably using a program like O&O Defrag in the Complete/NAME mode, as FSX is highly fragmented after install. (Note that this does not apply if you are using a Solid State Disk (SSD), defrag has no relevance to a drive that uses random access flash memory)

For FSX: Steam Edition:

Simply reinstall from your Steam games library.

How to set the FSX 2D panel view angle

Fri, 19 Feb 2010 21:08:36 GMT

To adjust the 2D Panel viewing angle up or down, use:

Down: Ctrl+Q
Up: Ctrl+Shift+Q

Fixing the FSX DLL Trust Policy

Fri, 19 Feb 2010 10:40:17 GMT

Overview:

When you load an FSX add-on aircraft for the first time, FSX should ask you if you trust the dlls (gauge files) when the airplane is first loaded. This should only happen the first time, or after a patch is applied to the add-on aircraft.

Occasionally, FSX will forget to ask you to authorize the dlls, and this can create an undesirable circumstances where the dlls (gauge files) are not loaded with the rest of the airplane. The end result is an unusable simulation.

Correcting the Problem:

The first step to correcting this problem is to open the FSX.CFG file and delete all references to your product that can be found under the [TRUSTED] section of the FSX.CFG.

Next, you must eliminate a troublesome registry setting that Windows uses for third party DLL trust policy selection.

Check if the HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing registry key is set to 0x63c00.

This value is Microsoft's WinTrust policy selection flags, as described here. The 0x40000 flag means "Allow only items in personal trust database" and apparently, this clashes with FSX's ability to allow manual authorization of unrecognized DLLs, telling it instead to never trust anything outside the user's personal trust.

Unsetting this flag (putting it back to its default 0x23c00 value) returns all operations to normal and Flight Simulator X will once again be able to ask the user to designate the PMDG DLL modules as 'Trusted' software.

(Thanks to Steve Patrick at Spat's Weblog for this)