Re: [RFC] New locking primitive for 2.5

Alan Cox
2002-02-08T23:56:18Z

> SMP 486s would need that (if there is such a beast). What point does x86
> get the 64 bit instructions? If after 586, then it would definately need a
> spinlock or somesuch in those functions.

There are SMP 486 class x86 machines that are MP 1.1 compliant. They are
sufficiently rare that I think its quite acceptable to "implement" a
cmpxchg8b macro on 486 as spin_lock_irqsave/blah/spin_unlock_irqrestore. It
would be wrong to cripple the other 99.99% of SMP users