AMD64 Linux documentation

[Jakub Jelinek]

On Fri, Dec 12, 2003 at 11:58:52AM -0500, Jeremy Katz wrote:
> > One additional thought/question ... OK, so you have /lib - /lib64 and /usr/lib 
> > - /usr/lib64 ... how does a program which needs a library get the "right" one 
> > since they are named the same?
> 
> The right library gets chosen because although they have the same name,
> they're not the same as far as what the DT_NEEDED is.  The DT_NEEDED for
> a 64bit library is something like libc.so.6(GLIBC_2.3.2)(64bit) instead
> of libc.so.6(GLIBC_2.3.2).  The x86_64 ldconfig can handle both ELF32
> and ELF64 and so sets the caches up correctly.  The right dynamic loader
> gets used because PT_INTERP gets set up correctly when the program is
> build (it references /lib64/ld-linux-x86-64.so.2)

DT_NEEDED contains just libc.so.6 for both 32-bit and 64-bit.  Symbol
version needs are in .gnu.version_r and 32-bit/64-bit is simple - a 32-bit
program/shared library always wants 32-bit dependencies, 64-bit
program/shlib wants 64-bit libraries.
What you wrote above are what rpm's provides/requires contain.

	Jakub