Re: Why Semaphore Hardware-Dependent?

David Howells
2006-08-29T16:25:30Z

Ralf Baechle <ralf@linux-mips.org> wrote:

> > Which arches do not support cmpxchg?
>
> MIPS, Alpha - probably any pure RISC load/store architecture.

Some of these have LL/SC or equivalent instead, but ARM5 and before, FRV, M68K
before 68020 to name but a few.

And anything that implements CMPXCHG with spinlocks is a really bad candidate
for CMPXCHG-based rwsems.

David