[uClibc]PowerPC crt0 problems

[David Schleef]

On Tue, May 15, 2001 at 12:41:24PM +0300, Michael Shmulevich wrote:
> Hello all,
> 
> I investigated futher a PowerPC problem and figured out that the crt0 
> initializer (curently present in CVS) works only in static compilation 
> code, but useless for dynamic linker, and vice versa the crt0 for 
> dynamic executable (taken from glibc) doesn't suit the static programs.


Ok, I think I figured out what was going on.  In the static case,
the kernel calls _start with the stack pointer pointing to 

   -->   argc
         argv[0]
         argv[1]
	 ..
	 null
	 envp[0]
	 envp[1]
	 ..
	 null

This is the "standard" Linux way of calling an application.  When
the dynamic linker calls _start, it calls with the stack pointer
set to &argc-0x10, which conveniently points to 0.  (There is
a good reason why this memory location should always be 0, since
it's part of the null stack frame that indicates the end of the
stack.)  So, I changed crt0.c to look at argc, and if it is 0,
increment the pointer by 16 bytes, to where argc really is.  It
seems to work now.

I made some irrelevant changes to the asm code in crt0.c; I
may remove those.

I have busybox running relatively ok both dynamically and statically.
There are still a few issues related to the TIOC ioctls, though.




dave...