I'm pretty sure the strong ordering of x86 is all in support of backward compatibility (probably to the first multi-core x86). One related example of this is t

I'm pretty sure the strong ordering of x86 is all in support of backward compatibility (probably to the first multi-core x86). One related example of this is the cache coherent I/O system. If a PCIe card writes to memory, there is really not much that the driver code needs to worry about compared with other processors. Why is this? So the ancient device drivers in MS-DOS will still work with the ancient floppy disk DMA controller.