On Wed, Dec 4, 2013 at 8:54 AM, H. Peter Anvin <h...@zytor.com> wrote: > > That is why I talk about the atomic instruction word... most (but not > *all*) architectures have a fundamental minimum unit of instructions > which is aligned and can be atomically written. Typically this is 1, 2, > or 4 bytes.
Note that it's not just about the "atomically written", it's also about the guarantee that it's atomically *read*. x86 can certainly atomically write a 4-byte instruction too, it's just that there's no guarantee - even if the instruction is aligned etc - that the actual instruction decoding always ends up reading it that way. It might re-read an instruction after encountering a prefix byte etc etc. So even if it's all properly aligned, the reading side might do something odd. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/