Unable to handle kernel NULL pointer dereference at virtual address 00000034             
pgd = c3aec000                                                                           
[00000034] *pgd=33ad7031, *pte=00000000, *ppte=00000000                                  
Internal error: Oops: 17 [#1]                                                            
last sysfs file: /sys/devices/virtual/vc/vcsa5/dev                                       
Modules linked in: virtual_bus1(+)                                                       
CPU: 0    Not tainted  (2.6.32.2-FriendlyARM #1)                                         
PC is at bus_add_device+0xbc/0x174                                                       
LR is at bus_add_device+0x18/0x174                                                       
pc : []    lr : []    psr: 60000013                                  
sp : c3b0de90  ip : c3b0de90  fp : c3b0deb4                                              
r10: 00000000  r9 : c3b0c000  r8 : c04ab958                                              
r7 : 00000000  r6 : bf000188  r5 : bf000220  r4 : bf000180                               
r3 : 00000000  r2 : c3b0de58  r1 : 00000000  r0 : bf000220                               
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user                        
Control: c000717f  Table: 33aec000  DAC: 00000015                                        
Process insmod (pid: 718, stack limit = 0xc3b0c270)                                      
Stack: (0xc3b0de90 to 0xc3b0e000)                                                        
de80:                                     bf000180 bf000188 00000000 00000000            
dea0: c04ab958 c3b0c000 c3b0defc c3b0deb8 c017ef40 c01805d0 00000000 00000000            
dec0: c3b0dee4 c3b0ded0 c014647c c014745c bf000180 bf000180 c3b0c000 00000000            
dee0: bf003000 c0030088 c3b0c000 00000000 c3b0df14 c3b0df00 c017f05c c017eb94            
df00: c04812a0 c3b0c000 c3b0df2c c3b0df18 bf003014 c017f050 c04812a0 c3b0c000            
df20: c3b0df7c c3b0df30 c002f32c bf003010 bf00014c 00000002 00000000 00000000            
df40: 00000000 000b8038 bf000258 00000000 00000edc 000b8038 bf000258 00000000            
df60: 00000edc c0030088 c3b0c000 00000000 c3b0dfa4 c3b0df80 c006e394 c002f300            
df80: c3b0dfa4 c3b0df90 00000005 00000069 bee66e74 00000080 00000000 c3b0dfa8            
dfa0: c002fee0 c006e2d8 00000005 00000069 000b8038 00000edc 000a3cd0 00000000            
dfc0: 00000005 00000069 bee66e74 00000080 bee66e78 000a3cd0 bee66e78 00000000            
dfe0: 00000001 bee66b24 0001852c 401c8984 60000010 000b8038 00000000 00000000            
Backtrace:                                                                               
[] (bus_add_device+0x0/0x174) from [] (device_add+0x3bc/0x4bc)       
 r9:c3b0c000 r8:c04ab958 r7:00000000 r6:00000000 r5:bf000188                             
r4:bf000180                                                                              
[] (device_add+0x0/0x4bc) from [] (device_register+0x1c/0x20)        
[] (device_register+0x0/0x20) from [] (virtual_bus_init+0x14/0x30 [v)
 r5:c3b0c000 r4:c04812a0                                                                 
[] (virtual_bus_init+0x0/0x30 [virtual_bus1]) from [] (do_one_initca)
 r5:c3b0c000 r4:c04812a0                                                                 
[] (do_one_initcall+0x0/0x1dc) from [] (sys_init_module+0xcc/0x1fc)  
[] (sys_init_module+0x0/0x1fc) from [] (ret_fast_syscall+0x0/0x28)   
 r7:00000080 r6:bee66e74 r5:00000069 r4:00000005                                         
Code: e1a00008 e89dabf0 e5953030 e2846008 (e5930034)                                     
---[ end trace 305c0d319c2b81f9 ]---          

This is my codes:
#include
#include
#include
#include
#include


static int virtual_bus_mach(struct device *device,struct device_driver *driver)
{
     printk(KERN_INFO"virtual bus is maching the device and drivern");
     return !strncmp(device->init_name,driver->name,strlen(driver->name));/*in the kernel 2.6.32 */
}

static int virtual_bus_release(struct device *device)
{ 
     printk(KERN_INFO"virtual bus is gone...n");
     return 0;
}

struct bus_type virtual_bus_type={
.name="virtual_bus",
.match=virtual_bus_mach,
};
EXPORT_SYMBOL(virtual_bus_type);
struct device virtual_bus={
.parent=NULL,
.init_name="virtual_bus",   /*in the kernel 2.6.32 */
.bus=&virtual_bus_type,
.release=virtual_bus_release,
};
EXPORT_SYMBOL(virtual_bus);
static int __init virtual_bus_init()
{
    int reg;
    reg=device_register(&virtual_bus);
    if(reg)
    {
       printk(KERN_INFO"can not register the virtual_bus");
       return reg;
    }
    return 0;  
}
static void __exit virtual_bus_exit()
{
    device_unregister(&virtual_bus);
    printk(KERN_INFO"virtual bus is gone..n");
}
module_init(virtual_bus_init);
module_exit(virtual_bus_exit);

MODULE_AUTHOR("Z_XLONG");
MODULE_LICENSE("GPL");

*********************************************
please help me,,when i am insmoding the module,kernel print Oops.But ,I can not understand the meaning !!!!

怎么死脑筋呢？virtual_bus_type如果没注册你要的设备挂到哪里呢？好好看看LDD吧