On one of my netra X1's that i just updated to the F-12 rawhide tree i got the 
following 
uname -a
Linux thor.ausil.us 2.6.31-0.149.rc5.git3.fc12.sparc64 #1 SMP Wed Aug 12 
03:02:38 UTC 2009 sparc64 sparc64 sparc64 GNU/Linux

We disabled the -smp kernel and are now only building a smp kernel. the netra 
has only a single cpu

BUG: spinlock bad magic on CPU#0, swapper/1 (Not tainted)                                                                                                               
 lock: fffff8006f2ce528, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0                                                                                             
Call Trace:                                                                                                                                                             
 [0000000000650f58] spin_bug+0x8c/0x9c                                                                                                                                  
 [0000000000651030] _raw_spin_lock+0x24/0x150                                                                                                                           
 [000000000084a30c] _spin_lock_bh+0x14/0x24                                                                                                                             
 [0000000000794d28] alloc_netdev_mq+0xf0/0x288                                                                                                                          
 [00000000006f49b4] loopback_net_init+0x20/0x84                                                                                                                         
 [000000000078d064] register_pernet_operations+0x38/0xe0                                                                                                                
 [000000000078d128] register_pernet_device+0x1c/0x5c                                                                                                                    
 [0000000000aaef04] net_dev_init+0x174/0x1f4                                                                                                                            
 [0000000000426d30] do_one_initcall+0x5c/0x188                                                                                                                          
 [0000000000a8e3a4] kernel_init+0x238/0x29c                                                                                                                             
 [000000000042b550] kernel_thread+0x38/0x50                                                                                                                             
 [0000000000832c1c] rest_init+0x18/0x80