[gcc r14-9093] pru: Document that arguments are not passed to main with -minrt

[Dimitar Dimitrov <dimitar@gcc.gnu.org>]

https://gcc.gnu.org/g:e3dfc150512c331805b8701e9117bd711025800a

commit r14-9093-ge3dfc150512c331805b8701e9117bd711025800a
Author: Dimitar Dimitrov <dimitar@dinux.eu>
Date:   Thu Feb 1 19:19:54 2024 +0200

    pru: Document that arguments are not passed to main with -minrt
    
    The minimal runtime has been documented from the beginning to break some
    standard features in order to reduce code size, while keeping
    the features required by typical firmware programs.  Document one more
    imposed restriction - the main() function must take no arguments.
    
    gcc/ChangeLog:
    
            * doc/invoke.texi (-minrt): Clarify that main
            must take no arguments.
    
    Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>

Diff:
---
 gcc/doc/invoke.texi | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index e18886e0ac7b..69020245b256 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -30091,11 +30091,18 @@ These command-line options are defined for PRU target:
 @table @gcctabopt
 @opindex minrt
 @item -minrt
-Link with a minimum runtime environment, with no support for static
-initializers and constructors.  Using this option can significantly reduce
-the size of the final ELF binary.  Beware that the compiler could still
-generate code with static initializers and constructors.  It is up to the
-programmer to ensure that the source program will not use those features.
+Link with a minimum runtime environment.  This can significantly reduce
+the size of the final ELF binary, but some standard C runtime features
+are removed.
+
+This option disables support for static initializers and constructors.
+Beware that the compiler could still generate code with static initializers
+and constructors.  It is up to the programmer to ensure that the source
+program will not use those features.
+
+The minimal startup code would not pass @code{argc} and @code{argv} arguments
+to @code{main}, so the latter must be declared as @code{int main (void)}.
+This is already the norm for most firmware projects.
 
 @opindex mmcu
 @item -mmcu=@var{mcu}