On 23 February 2017 at 10:10, Paolo Bonzini <pbonz...@redhat.com> wrote: > On 23/02/2017 11:02, Peter Maydell wrote: >> I'm really not convinced we need DEVICE_HOST_ENDIAN. RAM >> areas should be target-endian (you can probably define >> "target endianness" as "the endianness that RAM areas have".) > > This is not RAM. This is MMIO, backed by a MMIO area in the host.
Hmm, I see...the naming is a bit unfortunate if it's not RAM. > The > MemoryRegionOps read from the MMIO area (so the data has host > endianness) and do not do any further swap: > > data = *(uint16_t *)(mr->ram_block->host + addr); > > Here, the dereference is basically the same as ldl_he_p. > > If you wanted to make the MemoryRegion use DEVICE_NATIVE_ENDIAN, you'd > need to tswap around the access. Or you can use ldl_le_p and > DEVICE_LITTLE_ENDIAN (this is what Yongji's patch open codes), or > ldl_be_p and DEVICE_BIG_ENDIAN. They are all the same in the end. Using stl_p &c in a DEVICE_NATIVE_ENDIAN MR would work too, right? (This is how all the NATIVE_ENDIAN MRs in exec.c work.) thanks -- PMM
