They are used when ASLR is not applied. The need for adjusting is due to rtld direct exec mode puts ld-elf.so.1 at the PIE load address, and this address must not conflict with the default linker' load address for non-PIE binaries. Otherwise rtld in direct mode cannot activate image. Example of implicit failure is ldd(1) refusing to run. Reported by: kp
i386: move hard-coded load address for PIE below default linker base both for i386 native and compat32 amd64. We know the ld-elf.so.1 size in advance, it fits there. Trying to push it up after the end of a binary cannot work reliably and eventually fail for large binaries.