4GB OR only 2.2GB for single 32bit application in 64bit windows with 4GT and LARGE_ADDRESS_AWARE set? RRS feed

  • Question

  • Hello,

    Recently I used a software requiring a large memory. And I have tried to allocate more memory for this application, and I find some interesting phenomena which is different from the case I searched from Internet. Therefore, I am very curious about the mechanism of memory management of WoW64.

    With default setting, my application can only apply for 1.6GB memory (less than 2 GB barrier). And I use increaseuserva command by BCDedit, and it worked. With this setting, it can apply for 144 MB more memory (far less than 3 GB described on MSDN And then I modified the PE headers to add a LARGE_ADDRESS_AWARE flag, and it worked. The limit was changed to be 2.2GB, and it is far less than 4GB as they said!

    What happened? How can I increase the limit to 4 GB? 

    I have tried two systems 64bit Win7 home premium and 64bit Windows10 TP. 

    Could anybody tell me what is the problem is?

    Monday, February 2, 2015 6:10 PM


All replies

  • Windows uses a chunk of memory too.

    With 32 bit windows you will have.

    Windows memory usage, user program memory usage and graphics area.

    This will add to 4GB. Usually only <> 3.2 GB is available for use by windows etc.


    Monday, February 2, 2015 11:09 PM
  • My Ram is 8G, and my free memory is more than 6GB.
    Tuesday, February 3, 2015 7:51 AM
  • And it seems a limit of system, because I can only apply for such amount of memory and even if I apply for 1 MB more, there will be a error......

    Very wired thing......

    Tuesday, February 3, 2015 1:28 PM
  • I have tried testlimit, and it reserved 4GB......

    These software are designed for linux/unix, and now they compiled for windows. Maybe there is a problem with these software.

    Thank you very much.

    Tuesday, February 3, 2015 8:33 PM
  • I'd try them over here.





    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows]

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights.

    Saturday, February 7, 2015 12:04 AM