Question on PCIE compiler

[Altera_Forum]

I set up a project based on "Arria II GX FPGA Development Kit, 6G Edition (EP2AGX260)". 

 I encountered a problem: when I config the PCIE IP with a BAR space larger than 256MBytes, the WinDriver will give an error (System can detect the PCIE endpoint with correct device ID):" Failed opening a handle to the device: Failed opening a WDC device handle. Error 0x20000018 – Failed to map in kernel space."    What does it mean? How to solve it?   Jed

[Altera_Forum]

I think I know why. It is because the system space is not enough to map the device space. (My system is Windows XP. The total space is no more than 4GB. With 2GB memory, no more than 2GB is available for device space mapping). 

 Am I right?

[Altera_Forum]

On 32 bit Windows XP/Vista/7, there are two limitations. 

- As you said, there's a 4 GB physical address space that is shared by physical RAM and devices. Since you only have 2 GB of physical RAM, it's unlikely this is the cause -- unless you have tons of other devices.. ?  - The kernel has a 2 GB virtual address space into which is must map the kernel's code and data structures, plus the devices. This would be a more likely cause-  Additionally, I'm not sure if Windows or WinDriver even allow spaces larger than 256 MB. I say that because, as far as I can see , even graphic cards with 1GB of RAM only expose a 256 MB space.  In any case, it looks like an OS/Windriver limitation, not a firmware problem.