"Ramadass, Ramanathan" <Ramanathan.Ramadass@xxxxxxxxxxxxxx> writes: > 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; gcc proper only comes with basic runtime support routines, for things like long long arithmetic and exception handling. On some systems gcc also provides basic support for C++ global constructors and destructors. It is unlikely that you want to replace this. If you think you do, can you explain further? For C++, gcc also comes with libstdc++-v3 which is an implementation of the STL. You should be able to replace that directly with 3rd party code--assuming of course that you can recompile the 3rd party code to use the gcc mangling and ABI, or that the 3rd party code uses the same ABI. GNU/Linux comes with a large C library, but that is not part of gcc. > 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. I'm not sure precisely what you mean. gcc comes with what might be called a C runtime. The C standard libraries are not part of gcc; they are part of glibc. > 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. Basically, the gcc support is found in -lgcc, and the C library is found in -lc. So if you link against your 3rd party library instead of -lc, you will get the gcc runtime, but your 3rd party C library. gcc normally links against -lc automatically, but you can disable this using the -nostdlib option. See the documentation. Ian
