Hi, all: I'm working on an embedded system using PCIe bus. Now my task is to test the speed and correctness of the PCIe bus. In order to do that: 1. find the corresponding resource I want to read and write ---- /sys/bus/pci/devices/XXXX:XX:XX.X/resource0 2. in my program, use function open() to open the resource 3. remap it use mmap() like this: long *where = (long*) mmap( NULL, getpagesize(), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0) 4. then I can read and write through PCIe bus like this: where[0]; //read where[0] = 1; //write Is this the correct and entire process to test it in Linux? Besides, I also worry about the cache's effect. I will actually read/write the register of PCIe switch through PCIe bus. Presumably, they're actually IO from the perspective of Linux, and Linux should not cache it. Is it correct? Thanks a lot. Best, Hanks