Stratix 10M PCIe BAR0 size incorrect

Some more strange behavior. If I comment out the code to memset and msync, I can read entire kilobytes off data off of the bus. HOWEVER, I can only read it 32b at a time. If I try to memcpy a large number of bytes from the uio0, then I get 0xffff_ffff for all the readback data, which is incorrect. If I read the values in a loop 32b at a time, I get 0xdead_beef, which is the expected result.

So, it looks like there is something wrong with *writing* more than 16B at a time to uio0, but reading is fine...