On 30/04/12 09:51, Andrew Haley wrote: > On 04/27/2012 10:30 PM, Richard Henderson wrote: >> We can perform a single-copy atomic load with an ldrexd insn. >> If the load is all we care about, we need not pair this with >> a strexd. > > Can we? It's good to know. I have had a long email exchange with > engineers at ARM, and they would not say that this was safe. If they > have changed their mind, I'd like to see chapter and verse. > > Andrew. >
The ARM ARM lists a number of single-copy atomic operations. For v7, the list includes: - memory accesses caused by LDREXD and STREXD instructions to doubleword-aligned locations. Of course, there is a potential performance issue from heavy use of the global monitor to ensure coherency. R.
