内核dynamic_debug调试相关
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2022-05-29 09:12:14
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内核中有用pr_debug及dev_debug的log输出, 可以使用内核动态调试开关来选择。
具体操作如下:
1. make menconfig 使能 dynamic_debug相关配置
2. cat /sys/kernel/debug/dynamic_debug/control | grep "dwc3/gadget.c"
debug/control :/run/media/mmcblk0p1# cat /sys/kernel/debug/dynamic_debug/control | grep "dwc3/gadget.c"
drivers/usb/dwc3/gadget.c:814 [dwc3]dwc3_gadget_ep_enable =_ "dwc3: invalid parameters\012"_d
drivers/usb/dwc3/gadget.c:819 [dwc3]dwc3_gadget_ep_enable =_ "dwc3: missing wMaxPacketSize\012"
drivers/usb/dwc3/gadget.c:846 [dwc3]dwc3_gadget_ep_disable =_ "dwc3: invalid parameters\012"
drivers/usb/dwc3/gadget.c:2679 [dwc3]dwc3_endpoint_interrupt =_ "Stream %d found and started"
3. 此时动态打印时关闭的, 如何开启?
echo -n 'file gadget.c +p' > /sys/kernel/debug/dynamic_debug/control 即可
查看有啥区别
debug/control :/run/media/mmcblk0p1# cat /sys/kernel/debug/dynamic_debug/control | grep "dwc3/gadget.c"
drivers/usb/dwc3/gadget.c:814 [dwc3]dwc3_gadget_ep_enable =p "dwc3: invalid parameters\012"_d
drivers/usb/dwc3/gadget.c:819 [dwc3]dwc3_gadget_ep_enable =p "dwc3: missing wMaxPacketSize\012"
drivers/usb/dwc3/gadget.c:846 [dwc3]dwc3_gadget_ep_disable =p "dwc3: invalid parameters\012"
drivers/usb/dwc3/gadget.c:2679 [dwc3]dwc3_endpoint_interrupt =p "Stream %d found and started"
是滴...后面有个p...
ok, 不管咋样, 这样这个log就能输出了...
哦, 不对, 还是没看见相应log啊...
忘了一句 echo 8 > /proc/sys/kernel/printk
ok, 具体内容挺多, 也很灵活, 可参考内核文档:
Documentation/admin-guide/dynamic-debug-howto.rst
摘录一些内容:
208 The flags specification comprises a change operation followed
209 by one or more flag characters. The change operation is one
210 of the characters::
211
212 - remove the given flags
213 + add the given flags
214 = set the flags to the given flags
215
216 The flags are::
217
218 p enables the pr_debug() callsite.
219 f Include the function name in the printed message
220 l Include line number in the printed message
221 m Include module name in the printed message
222 t Include thread ID in messages not generated from interrupt context
223 _ No flags are set. (Or'd with others on input) 308 Examples
309 ========
310
311 ::
312
313 // enable the message at line 1603 of file svcsock.c
314 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
315 › › › › <debugfs>/dynamic_debug/control
316
317 // enable all the messages in file svcsock.c
318 nullarbor:~ # echo -n 'file svcsock.c +p' >
319 › › › › <debugfs>/dynamic_debug/control
320
321 // enable all the messages in the NFS server module
322 nullarbor:~ # echo -n 'module nfsd +p' >
323 › › › › <debugfs>/dynamic_debug/control
324
325 // enable all 12 messages in the function svc_process()
326 nullarbor:~ # echo -n 'func svc_process +p' >
327 › › › › <debugfs>/dynamic_debug/control
328
329 // disable all 12 messages in the function svc_process()
330 nullarbor:~ # echo -n 'func svc_process -p' >
331 › › › › <debugfs>/dynamic_debug/control
332
333 // enable messages for NFS calls READ, READLINK, READDIR and READDIR+.
334 nullarbor:~ # echo -n 'format "nfsd: READ" +p' >
335 › › › › <debugfs>/dynamic_debug/control ok, that's it.
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