PATCH: Check for lock without a lockable instruction

[Alan Modra]

On Thu, Nov 12, 2009 at 10:54:19AM -0800, H.J. Lu wrote:
> The lock prefix is valid only on add, adc, and, btc, btr, bts, cmpxchg,
> cmpxch8b, dec, inc, neg, not, or, sbb, sub, xor, xadd and xchg with
> a memory operand.

Is this true for old processors?  My recollection is that 286 and
earlier do not care.

-- 
Alan Modra
Australia Development Lab, IBM