libstdc++/4367: Sparc atomicity.h routines can lock up on some OS.

[Richard Henderson]

On Tue, Apr 02, 2002 at 02:56:22AM -0000, bkoz@gcc.gnu.org wrote:
>     I guess you'll have to use heavier-weight locks for these OS's.
>     Can you think of another solution? I cannot. 

Generally for these targets you turn off interrupts.  See
the m68k atomicity.h, for instance.

>     Note this is an issue with all the cpu/atomicity.h files,
>     not just sparc, right?

No, only those cpu's that have to use spinlocks instead of
e.g. an atomic-add, compare-and-exchange, or load-locked
instruction.

Of those listed in config/*, Sparc v7/v8, m68000, MIPS I,
and PA are affected.

MIPS I is an odd-ball because some operating systems (eg Linux)
provide emulation for the MIPS II ll/sc instructions.  Currently
our atomicity.h file assumes MIPS II.


r~