Trying to prove my PCIe works

Question

I'm using a Virtex-5 and the LogiCORE IP Endpoint Block Plus v1.15 for PCI Express on an OEM board.
I'm using write32(/*bar*/,/*offset*/,/*data*) and read32(/*bar*/,*offset*/) from linux (Fedora KDE 22) to go through my OEM's driver and access the Virtex-5.
The following sequence seems to prove that the driver, my physical PCIe connection, and my PCIe endpoint inside the Virtex-5 are working.  It accesses bar=0 and offset=0:
write32(0,0,0x00000000);
read32(0,0); // Returns 0x00000000 as expected
write32(0,0,0xFFFFFFFF);
read32(0,0); // Returns 0xFFFFFFFF as expected
However, when I access offset=1 it doesn't work:
write32(0,1,0x00000000);
read32(0,1); // Returns 0xFFFFFFFF which is NOT expected
write32(0,1,0xFFFFFFFF);
read32(0,1); // Returns 0xFFFFFFFF as expected
Any idea what I may be doing wrong?

Answer 1

Are you sure that the second argument is a word offset?  I would have thought that even though you're doing 32-bit reads you'd want a byte offset, so 4 would be the next usable location, not 1.