Finding ld.so dynamic loader

Michael Eager
2008-01-30T16:42:21Z

I've been reading through solib_open() in solib.c and the way
that the code searches for the dynamic loader doesn't make sense
to me, especially when using gdbserver to debug a program on
a remote system. Perhaps someone can explain to me why it is correct.

solib_open() is called by enable_break() with the name of
the dynamic loader, say, "/lib/ld.so.1". The comments at
the top of solib_open() say:

125 * If there is a solib_absolute_prefix and path is absolute:
126 * Search for solib_absolute_prefix/path.
127 * else
128 * Look for it literally (unmodified).
129 * Look in SOLIB_SEARCH_PATH.
130 * If available, use target defined search function.
131 * If solib_absolute_prefix is NOT set, perform the following two searches:
132 * Look in inferior's $PATH.
133 * Look in inferior's $LD_LIBRARY_PATH.

If solib_absolute_prefix is empty (true for almost all targets) and
/lib/ld.so.1 exists on the host system, this will be opened in
preference to either one specified on the SOLIB_SEARCH_PATH or using a
target search path.

This seems incorrect. The dynamic loader on the host system
may not be the same as on the target system, and in the case
of cross development, may not even have the same architecture.
Shouldn't the search using the unmodified name be the last choice,
not the first?

Can someone explain to me how gdb is supposed to find the correct
ld.so or why I'm looking at this incorrectly?