On Sat, Aug 06, 2022 at 10:53:16AM +0200, Christophe JAILLET wrote: > Hi, > > When a driver is using dev_err(), part of it is inlined and it: > - takes advantage of dev_fmt() [1] > - implements Printk Index [2] > > Printk Index works with some __builtin_constant_p() magic in it. > In case of a use in a probe, 99.99% of the time the log level and the format > will be constant and the logic for Printk Index will be put in place. > > > In case dev_err_probe(), the format will be an argument passed to the > function and will not be constant, so nothing will be generated in the > 'printk'_index section. > > > In case dev_err_probe(), a potential dev_fmt() defined in the drivers' file > can't be taken into consideration. > (trusting my grep, we never use in files that define dev_fmt() in the .c > file. I've not checked if it is true via #include "<something.h>") > > > Even if I've read [3], I don't fully understand the real need of this Printk > Index mechanism (at least for my own needs :)) > > > My questions are: > - is my analysis right? > - is the lack of these 2 functionalities (dev_fmt and Printk Index) > expected, when dev_err_probe() is used? > - if not, is it a issue? > - should it be at least documented? The printk index stuff is odd, and always seemed like a "check box" option that some people wanted for a niche enterprise market. It's up to them to keep that working well if they really need it, driver authors should not worry about this. thanks, greg k-h
