Enabling write-combining IO access in userspace

Question

I have a PCIe device with a userspace driver. I\'m writing commands to the device through a BAR, the commands are latency sensitive and amount of data is small (~64-bytes) so I

Answer 1

I don't know if this will help, but this is how I got write-combining working on PCIe. Granted, it was in kernel space, but this complies with the Intel documentation. It's worth trying if you're stuck.

Globally defined:

unsigned int __attribute__ ((aligned(0x20))) srcArr[ARR_SIZE];

In your function:

int *pDestAddr

for (i = 0; i < ARR_SIZE; i++) {
    _mm_stream_si32(pDestAddr + i, pSrcAddr[i]);
}