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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"_ddrivers/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"_ddrivers/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 › › › ›/dynamic_debug/control 316 317 // enable all the messages in file svcsock.c 318 nullarbor:~ # echo -n 'file svcsock.c +p' > 319 › › › › /dynamic_debug/control 320 321 // enable all the messages in the NFS server module 322 nullarbor:~ # echo -n 'module nfsd +p' > 323 › › › › /dynamic_debug/control 324 325 // enable all 12 messages in the function svc_process() 326 nullarbor:~ # echo -n 'func svc_process +p' > 327 › › › › /dynamic_debug/control 328 329 // disable all 12 messages in the function svc_process() 330 nullarbor:~ # echo -n 'func svc_process -p' > 331 › › › › /dynamic_debug/control 332 333 // enable messages for NFS calls READ, READLINK, READDIR and READDIR+. 334 nullarbor:~ # echo -n 'format "nfsd: READ" +p' > 335 › › › › /dynamic_debug/control
ok, that's it.
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