The highly useful atomic bit operations are prefixed with the 'lock' prefix in the SMP kernel to maintain their atomic properties when used outside of (and by) the spinlock and message code. Amongst other things this is needed for the invalidate handler, as all CPU's will invalidate at the same time without any locks.
Interrupt 13 floating point error reporting is removed. This facility is not usable on a multiprocessor board, nor relevant to the Intel MP architecture which does not cover the 80386/80387 processor pair.
The /proc filesystem support is changed so that the /proc/cpuinfo file contains a column for each processor present. This information is extracted from the data save by smp_store_cpu_info().