Qs about runtime support libs like crt0.o

[Rick Mann <rmann at latencyzero dot com>]

I'm tasked with bringing up an Xscale PXA320 board from scratch (no  
OS), using GNU tools. I can build simple code (no newlib) that works  
fine, but I'm having some trouble with newlib.

I want to thoroughly understand the GCC C runtime and associated  
glue, and so, I have some questions:

1) Does Newlib replace all the crtX.o files used by a typical GCC  
build? At first I thought not, but then I noticed it does built  
crt0.o. However, I haven't seen any of the other gcc-provided cr  
libraries (crti.o, crtbegin.o, crtend.o, crtn.o). Do I still need to  
use GCC's versions?

The problem is that I need to link with a linker script, and I think  
that requires calling ld directly, rather than letting gcc invoke  
collect2.

2) I'm a little overwhelmed by all the stuff a newlib build produces.  
There seem to be many options not covered by configure --help (for  
example, what is "interwork?"), and the resulting build seems to  
include a great many duplicates. It produced an "arm-elf" directory  
that contained several more directories ("be," "fpu," "interwork,"  
"newlib," "nofmult," "thumb"), many of which in turn contain a  
"newlib" directory, etc. There are multiple copies of libc.a, crt0.o,  
etc, presumably with various differences.

Is there something that explains the various additional options, and  
what gets built?

3) The README talks about how newlib uses build and host rather than  
GCC's build, host and target, but in that section does not say that  
target is reinterpreted to mean host. In other parts of the README,  
it implies (and even explicitly states) that "target" is  
reinterpreted by "configure" to do the right thing.

Okay, that's probably enough for now. I sure do appreciate any help.  
Thanks!

--
Rick