Some newbie questions

[Mark Phillips]

On Sat, 31 Jan 1998, John Breen wrote:

...
> 1.  In my previous uses, I ran into the problem of main calling __main, 
> which couldn't be found; since my code was very simple, I just stubbed 
> it out.  I've now found that __main is in libgcc.a, but I have to 
> explicitly link to it.  Is this right?

Well it depends how your compiler is setup and if you link via the gcc
front-end. If you use gcc to do the link then it will probably
automatically add it in - use "gcc -v" to see how it calls the linker.
Using gcc to invoke ld also means it will try and pickup a copy of libgcc
compiled with the same compiler options (ie. -msoft-float).

> 
> 2.  Linking in libgcc then required _exit and _cleanup.  I stubbed 
> _cleanup and made _exit an infinite loop.  Does this make sense?

Sounds reasonable to me.

> 
> 3.  I wanted to use rand() (I *believe* I'm using newlib-1.7.0).  For 
> some reason, this requires sbrk().  I don't feel comfortable stubbing 
> this, but I considered just having it return -1 and setting errno to 
> ENOMEM (which the man page says it should do on error).  Any ideas?

I'm surprised here, because newlib-1.7.1/newlib/libc/stdlib/rand.c does
appear to reference sbrk (or any other function).

Try it and see!!!

> 
> 4.  I can't get SingleStep to recognize the debugging information.  I 
> generate coff with -g, convert it to IEEE with objcopy, and then to 
> SDS's format with fromieee.  But all I can display is disassembled code.  
> Anyone else have experience with SDS? (I did see a thread about this in 
> the archive, but it didn't look like it was completely answered; I'd 
> call SDS, but I imagine they'd just try to sell me their compiler).

Well it works for me using gcc 2.7.2.x.

BUT - I had to hack the compiler to build m68k-elf which generates
ELF/DWARF files.

If you are interested, I could email you my patches - they basically tweak
the header files.

> 
> 5.  I've seen reference to remote debugging with gdb.  Is this possible 
> via the BDM on the '360?

Let me know if you get this working! I'm using SDS Singlestep over
ethernet on a VME card, but our "real" targer just has a serial and BDM
connector - currently using AMC BDM box (with lots of silly problems).

> 
> Thanks.  I'm sure I'll have more questions in the coming weeks.
> --
> John A. Breen
> jab3@hotmail.com
> 

Good Luck
Mark Phillips


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