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SubjectShared Library starter, ld.so

I know this is not a Kernel problem but... it is an
embedded system problem using Linux with a very
minimal (homemade) 'C' runtime library.

The dynamic linker, provided with RedHat 9 no longer
compiles with the de facto standard of having register
EDX point to function to be called before exit.

This is (was) the relevent rule:

#
# This is the entry point, usually the first thing in the text
# segment. The SVR4/i386 ABI (pages 3-31, 3-32) says that upon
# entry most registers' values are unspecified, except for:
#
# %edx Contains a function pointer to be registered with `atexit'.
# This is how the dynamic linker arranges to have DT_FINI
# functions called for shared libraries that have been loaded
# before this code runs.
#
# %esp The stack contains the arguments and environment:
# 0(%esp) argc
# 4(%esp) argv[0]
# ...
# (4*argc)(%esp) NULL
# (4*(argc+1))(%esp) envp[0]
# ...
# NULL

Now the register contains junk, so if it was used as a function-
pointer, the code will seg-fault.

How does code 'know' not to call this function? If this is
no longer used, then EDX must be set to zero to let the start-up
code know not to call it.

I tried to find the source-code for ld.so (ld-linux.so.2) used with
this version and was not able to find it anywhere.


Cheers,
Dick Johnson
Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips).
Why is the government concerned about the lunatic fringe? Think about it.

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