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 都可以正常工作，没有任何问题。但在某些情况下，访问 /dev/ttyS1 会引发以下两条“哎呀”消息。
我不知道从哪里开始追查这个原因，你能帮忙吗？
第一
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)
第二
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)