Re: [RFC PATCH v3 04/17] hw/net/xilinx_ethlite: Simplify by having configurable endianness

The Xilinx 'ethlite' device was added in commit b43848a100 ("xilinx: Add ethlite emulation"), being only built back then for a big-endian MicroBlaze target (see commit 72b675caac "microblaze: Hook into the build-system"). I/O endianness access was then clarified in commit d48751ed4f ("xilinx-ethlite: Simplify byteswapping to/from brams"). Here the 'fix' was to use tswap32(). Since the machine was built as big-endian target, tswap32() use means the fix was for a little endian host. While the datasheet (reference added in file header) is not precise about it, we interpret such change as the device expects accesses in big-endian order. Instead of having a double swapping, one in the core memory layer due to DEVICE_NATIVE_ENDIAN and a second one with the tswap calls, allow the machine code to select the proper endianness desired, removing the need of tswap(). Replace the DEVICE_NATIVE_ENDIAN MemoryRegionOps by a pair of DEVICE_LITTLE_ENDIAN / DEVICE_BIG_ENDIAN. Add the "little-endian" property to select the device endianness, defaulting to little endian. Set the proper endianness on the single machine using the device. Signed-off-by: Philippe Mathieu-Daudé <philmd(a)linaro.org&gt; --- RFC until I digest Paolo's review from v1: https://lore.kernel.org/qemu-devel/34f6fe2f-06e0-4e2a-a361-2d662f6814b5@r...

- r = tswap32(s->regs[addr]); + r = s->regs[addr];

@@ -161,23 +165,26 @@ eth_write(void *opaque, hwaddr addr, break; default:

- s->regs[addr] = tswap32(value); + s->regs[addr] = value; break;