On 04/07/2015 23:19, Michael S. Tsirkin wrote: > The fact that address_space_write/_read actually does a byteswap if > host!=target endian should probably be documented.
FWIW, it's not if host != target endian. It's if memory region endianness != target endianness. See memory_region_wrong_endianness. > Or maybe it should be changed: it seems likely that non-target-specific > devices > that use it do this incorrectly ATM. In particular, dma_memory_rw_relaxed > calls > address_space_rw and since DMA originates with devices I think there's very > little chance that these actually want a different behaviour depending on the > target endian-ness. > > Most likely, these only work correctly because DMA outside RAM > is highly unusual. They work correctly because of that, and because most devices *and* targets are little endian so you have no swap. On ppc64, which has TARGET_WORDS_BIGENDIAN, it probably wouldn't work correctly. Paolo
