Originally Posted by Aleron Ives
The printf function is part of the standard C library, not something GNU developed. I doubt you'd get in trouble for including stdio.h in your closed-source program.
For instance, if you look at the stdio.h that comes with CodeBlocks, you'll see that it's public domain and not GPL:
This discussion is getting off topic from the iView, though.
I don't know anything about codeblocks, nor did I claim that GNU developed the printf function, but it is specifically implemented, coded and included in glibc, which is lGPL.
Here is the comment at the beggining of glibc's printf.c source file (from stdio.h)
/* Copyright (C) 1991, 1995, 1996, 1997, 2001, 2004, 2006
Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
So even though common implementation of printf may be public domain, the specific implementation of printf as included in glibc is subject to the terms of the lGPL just like the rest of glibc. So if you statically link a basic C function like printf on your program then you should be required to release source.
It is possible to create closed source binaries under lGPL, but static linking is not allowed. Also, if you make any changes to glibc itself then your linked work will also be considered to be derivative and the source for both must be available.
Source for printf.c:
This is a bit off topic, but it relates to the topic of firmware, concerning whether or not the firmware was developed using any GNU tools/libraries or other possible GPL violations.
Back on topic, have you tested each of the ch 3/4 firmwares, and did you notice any differences between them?
Thanks and cheers!