Re: MIPS_ATOMIC_SET in sys_sysmips()

[Harald Koerfgen <Harald.Koerfgen@home.ivm.de>]

On 19-Dec-00 Maciej W. Rozycki wrote:
> On Mon, 18 Dec 2000, Jun Sun wrote:
>> What do we offer to machines without ll/sc?
> 
>  I asked Ralf for a clarification of the sysmips(MIPS_ATOMIC_SET, ...) 
> call before I write better code.  No response so far.  I'm now really
> cosidering implementing the Ultrix atomic_op() syscall -- at least it has
> a well-known defined behaviour. 

Another possibility would be to rely on the userland ll/sc emulation in the
kernel. The one in the linux-vr tree seems to be working well and can easily be
backported to Linux/MIPS.

Advantage: userland binary compatibility.
Disadvantage: possibility for a lot of context switches for userland atomic
operations.
 
Having a sysmips(MIPS_ATOMIC_SET, ...) or atomic_op() solution would probably a
lot faster.

Maybe we should implement both :)

-- 
Regards,
Harald