On 01/14/2014 09:08 AM, Matt Turner wrote: > On Tue, Jan 14, 2014 at 3:03 AM, Peter Zijlstra <pet...@infradead.org> wrote: >> On Tue, Jan 14, 2014 at 10:28:23AM +0800, Daniel J Blueman wrote: >>>> Peter, >>>> >>>> I found out that the build failure was caused by the fact that the >>>> __native_word() macro (used internally by compiletime_assert_atomic()) >>>> allows only a size of 4 or 8 for x86-64. The data type that I used is a >>>> byte. Is there a reason why byte and short are not considered native? >>> >>> It seems likely it was implemented like that since there was no existing >>> need; long can be relied on as the largest native type, so this should >>> suffice and works here: >> >> There's Alphas that cannot actually atomically adres a byte; I do not >> konw if Linux cares about them, but if it does, we cannot in fact rely >> on this in generic primitives like this. > > That's right, and thanks for the heads-up. Alpha can only address 4 > and 8 bytes atomically. (LDL_L, LDQ_L, STL_C, STQ_C). > > The Byte-Word extension in EV56 doesn't add new atomics, so in fact no > Alphas can address < 4 bytes atomically. >
Emulated with aligned 4 byte atomics, and masking. The same is true for arm, ppc, mips which, depending on cpu, also lack < 4 byte atomics. r~ -- 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/
