通过OOPS信息中PC寄存器的值可以知道出错指令的地址，通过栈回朔信息可以知道出错时的函数调用的关系，根据这两点可以很快定位错误。
修改drivers/net/ethernet/davicom/dm9000.c，在dm9000_probe函数中u32 id_val;下增加下面语句：
int *ptr =NULL; *ptr=0xff;
编译内核下载到开发板上，内核启动会出现如类似下信息：
Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = c0004000 [00000000] *pgd=00000000 Internal error: Oops: 805 [#1] PREEMPT SMP ARM Modules linked in: CPU: 1 PID: 1 Comm: swapper/0 Not tainted 3.14.0 #11 task: ee8a0000 ti: ee8a4000 task.ti: ee8a4000 PC is at dm9000_probe+0x1c/0x8f0 LR is at platform_drv_probe+0x18/0x48 pc : [<c0277cc8>] lr : [<c0247f7c>] psr: 60000153 sp : ee8a5e48 ip : 00000000 fp : 00000000 r10: c052a4fc r9 : 00000000 r8 : c0591e98 r7 : 00000000 r6 : ee97c810 r5 : ee97c800 r4 : 00000000 r3 : 000000ff r2 : 00000000 r1 : ee8a5de8 r0 : ee97c800 Flags: nZCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment kernel Control: 10c5387d Table: 4000404a DAC: 00000015 Process swapper/0 (pid: 1, stack limit = 0xee8a4240) Stack: (0xee8a5e48 to 0xee8a6000) 5e40: ee975cf0 00000000 ee1503a8 00000001 c0561afc ee150438 5e60: 00000000 ee97c810 c0591e98 ee97c810 00000000 c0591e98 c0561afc c052a4fc 5e80: 00000000 c0247f7c c0247f64 c05d931c c0591e98 c0246668 ee97c810 c0591e98 5ea0: ee97c844 00000000 c054332c c0246804 c0591e98 c0246778 00000000 c0244fbc 5ec0: ee805478 ee9771c0 c0591e98 eeb73a00 c0590028 c0245e28 c04c3128 c0591e98 5ee0: 00000000 c0591e98 00000000 c054e2ac c059f280 c0246e1c 00000000 ee8a4000 5f00: 00000000 c00087b4 ee903b00 c05c3d50 60000153 c0571c00 60000100 c0571c00 5f20: 00000000 00000000 c0571bfc 00000000 c0505bc8 ef7fc918 00000089 c0034c6c 5f40: c04ca680 c0505338 00000006 00000006 00000000 c054e2c8 c054e2cc 00000006 5f60: c054e2ac c059f280 00000089 c052a4fc 00000000 c052ac4c 00000006 00000006 5f80: c052a4fc c003e0dc 00000000 c03b46ec 00000000 00000000 00000000 00000000 5fa0: 00000000 c03b46f4 00000000 c000e4b8 00000000 00000000 00000000 00000000 5fc0: 0000000000000000 00000000 00000000 00000000 00000000 00000000 00000000 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000 ffffffff ffffffff [<c0277cc8>] (dm9000_probe) from [<c0247f7c>] (platform_drv_probe+0x18/0x48) [<c0247f7c>] (platform_drv_probe) from [<c0246668>] (driver_probe_device+0x100/0x210) [<c0246668>] (driver_probe_device) from [<c0246804>] (__driver_attach+0x8c/0x90) [<c0246804>] (__driver_attach) from [<c0244fbc>] (bus_for_each_dev+0x58/0x88) [<c0244fbc>] (bus_for_each_dev) from [<c0245e28>] (bus_add_driver+0xd8/0x1cc) [<c0245e28>] (bus_add_driver) from [<c0246e1c>] (driver_register+0x78/0xf4) [<c0246e1c>] (driver_register) from [<c00087b4>] (do_one_initcall+0x30/0x144) [<c00087b4>] (do_one_initcall) from [<c052ac4c>] (kernel_init_freeable+0xfc/0x1c8) [<c052ac4c>] (kernel_init_freeable) from [<c03b46f4>] (kernel_init+0x8/0xe4)
错误分析：
1、第一行，说明是空指针造成的错误
Unable to handle kernel NULL pointer dereference at virtual address 00000000
2、寄存器信息主要是PC的值
PC is at dm9000_probe+0x1c/0x8f0 pc : [<c0277cc8>]
方法一、错误定位
arm-none-linux-gnueabi-objdump -D vmlinux > vmlinux.dis
文件vmlinux.dis非常大打开需要一定时间
对于大多数情况，从反汇编代码定位到C代码并不会如此容易，需要有较强的阅读汇编代码的能力。
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方法二、错误定位
通过addr2line去定位
arm-none-linux-gnueabi-addr2line 0xc0277cc8-e vmlinux -f