On 01/14/2014 01:01 PM, Richard Henderson wrote:
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.
I would like to know if the action of writing out a byte (e.g. *byte =
0) is atomic in those architectures or is emulated by a
compiler-generated software read-modify-write.
-Longman
--
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/
