Hi Massimo,
On Tue, 15 Aug 2023 at 13:01, Massimo Pegorer massimo.pegorer+oss@gmail.com wrote:
Hi
I had a trip into U-Boot logging and I am quite confused. I read the documentation at doc/develop/logging.rst and had a look at source code in log.h log.c printk.h Kconfig and other files, but the picture is still quite foggy and, let's say, 'complicated'.
The documentation does not mention at all CONFIG_LOGLEVEL, but pr_xxx macros rely on its value (and then on log_xxx macros). While log_xxx definitions, instead, depends on CONFIG_LOG and other CONFIG_LOG_XXX values.
It is not clear when/if pr_xxx and/or log/log_xxx should be used. Is any preferred and why? Is there a specific reason to keep both?
Neither the constrains and relations between Kconfig variables are clear. CONFIG_LOGLEVEL and CONFIG_LOG are in different section of menuconfig: Console and Logging. The semantic is also a little bit different: for LOGLEVEL, values smaller than the console loglevel will be compiled in; for LOG_MAX_LEVEL, instead, any value higher than this will be ignored.
The doc states that 'If CONFIG_LOG is not set, then no logging will be available'. But a few lines below 'If logging is disabled, the default behaviour is to output any message at level LOGL_INFO and below'. This sounds inconsistent to me.
I see a lot of To Do tasks listed in logging.rst, like converting some other logging statements like debug() and error(). I wonder if something can be improved, and in case how: I could commit some of my spare time.
Yes, you are right and this is a good analysis. The todo you found [1] is a good starting point, but anything you are able to contribute would be valuable.
One point I'll mention is that we do what to support the kernel-style logging so that code is easy to bring over. But those macros could be converted to use U-Boot logging. Then the log-level problem you mention could be resolved.
Regards, Simon
[1] https://u-boot.readthedocs.io/en/latest/develop/logging.html#to-do