Dear Jeroen,
In message 54384450.3000204@myspectrum.nl you wrote:
If you ask to disable it, it is good if it does so, don't see a problem with that. Anyway, it is not an u-boot issue, anything below -O2 is not supported anyway.
I'm not sure what you mean here. Gcc certainly does this replacement with -Os as used for U-Boot.
I would almost take this as an insult, I hope u-boot folks know or at least check before they assume a compiler does XYZ. And yes compilers will replace simple printf call with their simpler equivalent and has been doing so for quite a while (and that is an understatement).
I wonder how many people know about this - and where it is documented?
So to turn it around: just use printf: "you don't lose much but you can only win."
Sorry, but I disagree here.
First, we have a compatibility problem here. GCC assumes that puts() will add a newline character after the string; U-Boot puts() does NOT do this. So the GCC auto-converted printf()s will all be wrong, as they are missing the newline. [1]
Second, using puts() insteas of printf() is also a means of documenting your code. It shows your intention to print a constant string. Just one example: compare
A: void add_header(const char *s) { printf("MY HEADER: %s\n", s); }
versus
B: void add_header(const char *s) { puts("MY HEADER: "); puts(s); /* Assuming U-Boot puts() - no automatic \n added */ putc('\n'); }
Which is "better"? A is obviously much shorter and more elegant; but B is much more robust - A will happily crash your system when you try to print a string like "s%s%s%s%s%s%s%s%s%s%s" (not to mention that this may open a classic attack vector to break into a running system).
So yes, it does make sense to explicitly use puts().
[1] One might argue that this is a bug in U-Boot and should be fixed, but that is another topic.
Best regards,
Wolfgang Denk