Dear Jeroen,
In message <54384450.3000...@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
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
A verbal contract isn't worth the paper it's written on.
-- Samuel Goldwyn
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