Access hardware from user process

Question

I have a driver that runs in the kernel of a Windows Embedded Compact 2013. The driver is loaded with the "Drivers\BuiltIn" registry key. It accesses a set of HW-registers that are mapped with MmMapIoSpace.

The access to the hardware has some problems. That's why I would like to develop the hardware access in a user mode program and debug the problems. I created a program with VS2013 for that purpose. That's the way we used to go with Windows CE 5.0.

The driver maps the physical address with MmMapIoSpace to the process address space. My program should do the same or something similar. Unfortunately this doesn't work in my program. MmMapIoSpace returns NULL, LastError=87 (invalid parameters). Even CreateStaticMapping returns NULL.

How can I access memory mapped register in WEC2013 without building a new platform for each iteration?

score 1 · Accepted Answer · answered Aug 28 '14 at 15:39

MmMapIoSpace doesn't work in applications anymore since WinCE6. You maybe could create a driver which maps your hw-register to your user process. Your user process would then obtain this pointer by an ioctl call to this driver. We mapped some external memory to an application with this method. VirtualAllocCopyEx() can create a mapping to a specified process. Hope, this helps. Greetings.

score 0 · Answer 2 · answered Sep 02 '14 at 05:36

Corresponding to timmfs answer I implemented this code in the driver's XXX_IOControl function:

PHYSICAL_ADDRESS PhysAddress = { 0 };
PhysAddress.LowPart = phys_address;
PVOID pRegister = MmMapIoSpace(PhysAddress, phys_size, FALSE);

HANDLE hCallerProcess = (HANDLE)GetCallerVMProcessId();
HANDLE hCurrentProcess = (HANDLE)GetCurrentProcessId();
PVOID UserSpaceAddress = VirtualAllocCopyEx(hCurrentProcess, hCallerProcess, pRegister, shys_size, PAGE_NOCACHE);

This excerpt shows some solutions for pitfalls I met. So I show how I get all the parameters.

Access hardware from user process

2 Answers2