Hi,

I've encountered two problems with 2.6.16 and newer kernels on my API 
CS20 (dual 833MHz Alpha 21264b processors).  The first is the kernel 
OOPSing because of a NULL pointer dereference while trying to populate 
SysFS with the CPU information.  The other is that only one processor 
was being brought up.  I've included a small Alpha-specific patch that 
fixes both problems.

The first problem was caused by the CPUs never being properly registered 
using register_cpu(), the way it's done on other architectures.  I've 
added an arch_initcall called alpha_init that is modelled after the 
ppc_init arch_initcall.

The second problem has to do with the removal of hwrpb_cpu_present_mask 
in arch/alpha/kernel/smp.c.  In setup_smp() in the 2.6.15 kernel 
sources, hwrpb_cpu_present_mask has a bit set for each processor that is 
probed, and afterwards cpu_present_mask is set to the cpumask for the 
boot CPU.  In the same function of the same file in the 2.6.16 sources, 
instead of hwrpb_cpu_present_mask being set, cpu_possible_map is updated 
for each probed CPU.  cpu_present_mask is still set to the cpumask of 
the boot CPU afterwards.  The problem lies in include/asm-alpha/smp.h, 
where cpu_possible_map is #define'd to be cpu_present_mask.  My patch 
just replaces the #define with an actual cpumask_t declaration for 
cpu_possible_map since it is used separately from cpu_present_mask in 
the Alpha SMP code.

Regards,
Brian Uhrain