如何在嵌入式系统上调试内核 oops
我在嵌入式开发中遇到了其中一个串行端口的问题。 /dev/ttyS0、/dev/ttyS2 和 /dev/ttyS3 都工作正常，没有任何问题。 但在某些情况下，访问 /dev/ttyS1 会抛出以下两条“oops”消息。
我不知道从哪里开始追踪这个问题的原因，你能帮忙吗？
第 1 个
Unable to handle kernel NULL pointer dereference at virtual address 0000013c
pgd = c0004000
[0000013c] *pgd=00000000
stopped custom tracer.
Internal error: Oops: 17 [#1] PREEMPT
Modules linked in: macb
CPU: 0 Not tainted (2.6.24-rc5-rt1 #2)
pc : [<c01a9e60>] lr : [<c01a9e90>] psr: 60000093
sp : c3c25f10 ip : 0000012c fp : c3c25f1c
r10: 00000000 r9 : 00000000 r8 : 00000000
r7 : 000000ac r6 : 00000000 r5 : 0000012c r4 : 00000000
r3 : 60000093 r2 : 60000013 r1 : c3c1a340 r0 : 0000012c
Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 0005317f Table: 23dcc000 DAC: 00000017
Process softirq-high/0 (pid: 4, stack limit = 0xc3c24258)
Stack: (0xc3c25f10 to 0xc3c26000)
5f00: c3c25f2c c3c25f20 c01a9e90 c01a9e20
5f20: c3c25f44 c3c25f30 c0101b84 c01a9e90 c020ab48 c020abf4 c3c25f74 c3c25f48
5f40: c0119960 c0101b78 c3c1a340 c020ac2c 000f4240 00000000 00000004 00000000
5f60: c0205b78 c02059c8 c3c25f98 c3c25f78 c003cf5c c0119560 00000001 fffffffe
5f80: c02059d4 c3c24000 00000001 c3c25fa8 c3c25f9c c003d038 c003cee4 c3c25fd8
5fa0: c3c25fac c003d9ec c003d010 00000032 c3c24000 c02059c8 c003d8a0 00000000
5fc0: 00000000 00000000 00000000 c3c25ff4 c3c25fdc c004cc94 c003d8b0 00000000
5fe0: 00000000 00000000 00000000 c3c25ff8 c003b13c c004cc4c 00000000 00000000
Backtrace:
Function entered at [<c01a9e10>] from [<c01a9e90>]
Function entered at [<c01a9e80>] from [<c0101b84>]
Function entered at [<c0101b68>] from [<c0119960>]
r5:c020abf4 r4:c020ab48
Function entered at [<c0119550>] from [<c003cf5c>]
Function entered at [<c003ced4>] from [<c003d038>]
r8:00000001 r7:c3c24000 r6:c02059d4 r5:fffffffe r4:00000001
Function entered at [<c003d000>] from [<c003d9ec>]
Function entered at [<c003d8a0>] from [<c004cc94>]
Function entered at [<c004cc3c>] from [<c003b13c>]
r6:00000000 r5:00000000 r4:00000000
Code: e592100c e10f2000 e3823080 e121f003 (e59c3010)
第 2 个
Unable to handle kernel NULL pointer dereference at virtual address 000000bc
pgd = c0004000
[000000bc] *pgd=00000000
Internal error: Oops: 17 [#2] PREEMPT
Modules linked in: macb
CPU: 0 Tainted: G D (2.6.24-rc5-rt1 #2)
pc : [<c0101868>] lr : [<c01161c0>] psr: 60000013
sp : c3c33f50 ip : c3c33f68 fp : c3c33f64
r10: c0205ab8 r9 : c0205b78 r8 : 00000000
r7 : 00000004 r6 : 00000000 r5 : 000f4240 r4 : c3e3c378
r3 : c3e3c360 r2 : 60000013 r1 : a0000013 r0 : 00000000
Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 0005317f Table: 23dcc000 DAC: 00000017
Process softirq-tasklet (pid: 9, stack limit = 0xc3c32258)
Stack: (0xc3c33f50 to 0xc3c34000)
3f40: c3e3c378 000f4240 c3c33f74 c3c33f68
3f60: c01161c0 c010186c c3c33f98 c3c33f78 c003cf5c c01161b8 00000020 ffffffdf
3f80: c0205ac4 c3c32000 00000020 c3c33fa8 c3c33f9c c003d078 c003cee4 c3c33fd8
3fa0: c3c33fac c003d9ec c003d050 00000032 c3c32000 c0205ab8 c003d8a0 00000000
3fc0: 00000000 00000000 00000000 c3c33ff4 c3c33fdc c004cc94 c003d8b0 00000000
3fe0: 00000000 00000000 00000000 c3c33ff8 c003b13c c004cc4c ffffffff ffffffff
Backtrace:
Function entered at [<c010185c>] from [<c01161c0>]
r5:000f4240 r4:c3e3c378
Function entered at [<c01161a8>] from [<c003cf5c>]
Function entered at [<c003ced4>] from [<c003d078>]
r8:00000020 r7:c3c32000 r6:c0205ac4 r5:ffffffdf r4:00000020
Function entered at [<c003d040>] from [<c003d9ec>]
Function entered at [<c003d8a0>] from [<c004cc94>]
Function entered at [<c004cc3c>] from [<c003b13c>]
r6:00000000 r5:00000000 r4:00000000
Code: c01f63a4 e1a0c00d e92dd830 e24cb004 (e59030bc)
I've got a problem with one of the serial ports on an embedded development. /dev/ttyS0, /dev/ttyS2, and /dev/ttyS3 all work fine with no problems. But in some cases accessing /dev/ttyS1 throws the following two 'oops' messages.
I've no idea where to even start tracking down the cause of this, can you help?
1st
Unable to handle kernel NULL pointer dereference at virtual address 0000013c
pgd = c0004000
[0000013c] *pgd=00000000
stopped custom tracer.
Internal error: Oops: 17 [#1] PREEMPT
Modules linked in: macb
CPU: 0 Not tainted (2.6.24-rc5-rt1 #2)
pc : [<c01a9e60>] lr : [<c01a9e90>] psr: 60000093
sp : c3c25f10 ip : 0000012c fp : c3c25f1c
r10: 00000000 r9 : 00000000 r8 : 00000000
r7 : 000000ac r6 : 00000000 r5 : 0000012c r4 : 00000000
r3 : 60000093 r2 : 60000013 r1 : c3c1a340 r0 : 0000012c
Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 0005317f Table: 23dcc000 DAC: 00000017
Process softirq-high/0 (pid: 4, stack limit = 0xc3c24258)
Stack: (0xc3c25f10 to 0xc3c26000)
5f00: c3c25f2c c3c25f20 c01a9e90 c01a9e20
5f20: c3c25f44 c3c25f30 c0101b84 c01a9e90 c020ab48 c020abf4 c3c25f74 c3c25f48
5f40: c0119960 c0101b78 c3c1a340 c020ac2c 000f4240 00000000 00000004 00000000
5f60: c0205b78 c02059c8 c3c25f98 c3c25f78 c003cf5c c0119560 00000001 fffffffe
5f80: c02059d4 c3c24000 00000001 c3c25fa8 c3c25f9c c003d038 c003cee4 c3c25fd8
5fa0: c3c25fac c003d9ec c003d010 00000032 c3c24000 c02059c8 c003d8a0 00000000
5fc0: 00000000 00000000 00000000 c3c25ff4 c3c25fdc c004cc94 c003d8b0 00000000
5fe0: 00000000 00000000 00000000 c3c25ff8 c003b13c c004cc4c 00000000 00000000
Backtrace:
Function entered at [<c01a9e10>] from [<c01a9e90>]
Function entered at [<c01a9e80>] from [<c0101b84>]
Function entered at [<c0101b68>] from [<c0119960>]
r5:c020abf4 r4:c020ab48
Function entered at [<c0119550>] from [<c003cf5c>]
Function entered at [<c003ced4>] from [<c003d038>]
r8:00000001 r7:c3c24000 r6:c02059d4 r5:fffffffe r4:00000001
Function entered at [<c003d000>] from [<c003d9ec>]
Function entered at [<c003d8a0>] from [<c004cc94>]
Function entered at [<c004cc3c>] from [<c003b13c>]
r6:00000000 r5:00000000 r4:00000000
Code: e592100c e10f2000 e3823080 e121f003 (e59c3010)
2nd
Unable to handle kernel NULL pointer dereference at virtual address 000000bc
pgd = c0004000
[000000bc] *pgd=00000000
Internal error: Oops: 17 [#2] PREEMPT
Modules linked in: macb
CPU: 0 Tainted: G D (2.6.24-rc5-rt1 #2)
pc : [<c0101868>] lr : [<c01161c0>] psr: 60000013
sp : c3c33f50 ip : c3c33f68 fp : c3c33f64
r10: c0205ab8 r9 : c0205b78 r8 : 00000000
r7 : 00000004 r6 : 00000000 r5 : 000f4240 r4 : c3e3c378
r3 : c3e3c360 r2 : 60000013 r1 : a0000013 r0 : 00000000
Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 0005317f Table: 23dcc000 DAC: 00000017
Process softirq-tasklet (pid: 9, stack limit = 0xc3c32258)
Stack: (0xc3c33f50 to 0xc3c34000)
3f40: c3e3c378 000f4240 c3c33f74 c3c33f68
3f60: c01161c0 c010186c c3c33f98 c3c33f78 c003cf5c c01161b8 00000020 ffffffdf
3f80: c0205ac4 c3c32000 00000020 c3c33fa8 c3c33f9c c003d078 c003cee4 c3c33fd8
3fa0: c3c33fac c003d9ec c003d050 00000032 c3c32000 c0205ab8 c003d8a0 00000000
3fc0: 00000000 00000000 00000000 c3c33ff4 c3c33fdc c004cc94 c003d8b0 00000000
3fe0: 00000000 00000000 00000000 c3c33ff8 c003b13c c004cc4c ffffffff ffffffff
Backtrace:
Function entered at [<c010185c>] from [<c01161c0>]
r5:000f4240 r4:c3e3c378
Function entered at [<c01161a8>] from [<c003cf5c>]
Function entered at [<c003ced4>] from [<c003d078>]
r8:00000020 r7:c3c32000 r6:c0205ac4 r5:ffffffdf r4:00000020
Function entered at [<c003d040>] from [<c003d9ec>]
Function entered at [<c003d8a0>] from [<c004cc94>]
Function entered at [<c004cc3c>] from [<c003b13c>]
r6:00000000 r5:00000000 r4:00000000
Code: c01f63a4 e1a0c00d e92dd830 e24cb004 (e59030bc)
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评论（4）
您能做的最好的事情就是查看 Documentation/oops-tracing。文本
它解释了如何开始调试它。
您可以尝试的第一件事是解码回溯。 system.map 文件应该包含内核中所有函数的地址。 您应该能够通过这种方式生成可读的回溯。
The best thing you can do is to take a look at Documentation/oops-tracing.txt
It explains how you can start debugging this.
The first things you can try is decoding the backtrace. The system.map file should contain the addresses of all functions in your kernel. You should be able to produce a readable backtrace this way.
看看 http://lwn.net/Kernel/LDD3/ 并下载第 4 章滚动直到第 94 页。
最简单的方法是使用调试信息 (CONFIG_DEBUG_INFO) 编译内核并从 gdb 执行内核。
对于较旧的内核 (2.4)，您将需要 ksymoops。
Have a look at http://lwn.net/Kernel/LDD3/ and download chapter 4 scroll down to page 94.
The easiest way would be to compile your kernel with debug info (CONFIG_DEBUG_INFO) and execute the kernel from gdb.
For an older kernel (2.4) you will need ksymoops.
确保 ksymoops 已启用
或者查看 System.map 中的回溯值
或者获取 JTAG :)
Make sure that ksymoops is enabled
Or look backtrace values in the System.map
Or get a JTAG :)
您应该查看随内核生成的 system.map。 感谢这个文件，您将能够轻松解码您的 oops 回溯。
You should take a look at the system.map that is generated with your kernel. Thanks to this file you'll be enable to decode your oops backtrace easily.