GCC C/C++ runtime library question

[Ramadass, Ramanathan]

Hi,

I had posted the following on comp.compilers group and somebody helpfully pointed me to this list. 

I am trying to replace the standard C and C++ libraries which comes
with a Linux distro with our own(licensed from a 3rd party vendor). We
will be providing the lower level layer which the C/C++ library
uses(i.e. the system calls). What i would like to do is replace the
standard and the runtime libraries which come with gcc with our own. I
am a newbie in this and hence have some basic questions;
 
1. What is the exact difference between the C runtime and the C
standard libraries i.e where does one end and the other begin;
specifically w.r.t gcc? While i am going through a lot of text(both
online and book form) i am not 100% clear on this.
 
2. In a gcc distribution where exactly does the compiler specific
magic lie within the runtime libraries? I might have to modify gcc to
use only my libraries but where and how do i begin? Currently i have
built the 3rd party vendor's library and am linking with it but for
some symbols i still have to go to the gcc runtimes. I am running "nm"
and extracting the object modules using "ar" for all the unresolved
symbols; which seems to be a roundabout way of doing things. What i
would like is to understand the structure of how gcc interfaces with
its runtimes. Would appreciate any and all help on this. Pointers to
other articles/links/books will also be very welcome.

Thanks
Ram