![]() The answer is lying in the dynamic_debug.h and since it's used during compilation the _DPRINTK_FLAGS_DEFAULT defines the certain message appearence. The "How certain debug prints are automatically enabled in linux kernel?" raises the question why some debug prints are automatically enabled and how DEBUG affects that when CONFIG_DYNAMIC_DEBUG=y. Using debug (fmt, args.): you can define DEBUG in the file u-boot- include/configs/common.h (like in my. How can I print more debug information from U-boot In the normal U-boot boot process,a limited amount of information is printed to the console.More details are described in the Dynamic Debug documentation. To enable more messages you can either: Using debugcond (cond, fmt, args.): if you define some cond, once it is met, the U-boot will print out this message. If the same driver is compiled as loadable module we may either add options 8250 dyndbg to the modprobe configuration or to the shell command line when do it manually, like modprobe 8250 dyndbg. To achieve that we simple add to the kernel command line the following 8250.dyndbg= p. Since it's limited and circular, newer data preempts old one.Īdditional information how to enable Dynamic Debug.įirst of all, be sure you have CONFIG_DYNAMIC_DEBUG=y in the kernel configuration.Īssume we would like to enable all debug prints in the built-in module with name 8250. Note, data in 2 is kept as long as there still room in the buffer. Internal buffer which can be read by running dmesg command.Current console if kernel loglevel value (can be changed via kernel command line or via procfs) is high enough for certain message, here KERN_DEBUG.and nothing else) but I am still seeing all current date main DEBUG messages. The logged message at the end is printed to If you get a Boot message, it means that the Xfinity Box is booting. Thus, obviously, the buffer is all the same, i.e. Just note here, that the rest functions like dev_err() will end up in the same function. This very same function is called in a normal mode when you just do a printk(). #if defined(CONFIG_DYNAMIC_DEBUG)Äynamic_dev_dbg(dev, format, #_VA_ARGS_) \Äev_printk(KERN_DEBUG, dev, format, #arg)Äev_printk(KERN_DEBUG, dev, format, #arg) \Äynamic_dev_dbg() and dev_printk() call dev_printk_emit() which calls vprintk_emit(). Dev_dbg() expands to dynamic_dev_dbg(), dev_printk(), or no-op depending on the compilation flags.
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