RFR: 8185723: Zero: segfaults on Power PC 32-bit

[Andrew Haley]

On 03/08/17 10:32, John Paul Adrian Glaubitz wrote:

> Btw, I'm currently trying to wrap my head around how to implement
> atomic_copy64() on m68k with inline assembly using cas2 which allows
> compare-and-swap with two 32-bit values and hence the implementation
> of an atomic_copy64().
> 
> I think either __arch_compare_and_exchange_val_64_acq() or
> atomic_exchange_acq() from [1] should help.

The first one is what you want, assuming that you're happy to
write to an operand you're supposed to only read.

But there may be a better way of handling atomic doublewords on the
68k.  Instead, define an array of lock words and yield on one of them
when reading or writing a doubleword.  That way you (probably) only
block when two threads really are contending, and the instant you
detect contention you yield.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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