Clarification on PowerPC64 Linux ABI

[Rohit Arul Raj <rohitarulraj at gmail dot com>]

Hello All,

I have a question regarding PowerPC64 bit ABI. Since GCC generates FP
instructions for Non FP code, i was running in to issues with
applications having interrupts (i have seen some threads with people
complaining about this). So the other option to resolve this was to
build the entire application with '-msoft-float' compiler option. It
seems to work fine with 32-bit PPC.

But when i tried to do the same with 64bit PPC, i was getting 'cannot
find -lgcc' error which was due to the MULTILIB option, that has been
set to exclude building target libraries with '-msoft-float -m64'
compiler option.

I have discussed this in the IRC channel some one mentioned that it is
because of 64bit ABI restriction even though some PPC Linux kernels
are built using this option.

I have gone through the ABI doc in the link given
"http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html";
and there is no mention of 'soft-float' or floating point emulation.
So it means i have to assume that '-msoft-float' is not defined by
ABI?

I have also gone through 32-bit PPC Linux ABI (sys V) doc,
"http://refspecs.freestandards.org/elf/elfspec_ppc.pdf"; and there is
no mention of 'soft-float' or floating point emulation either.

But the PPC EABI doc does have reference to soft-float/FP emulation
[CHAPTER 6 Libraries 20 - Software Floating Point Emulation Support
Routines].
http://sources-redhat.mirrors.airband.net/binutils/ppc-docs/ppc-eabi-1995-01.pdf

1. Am i referring right documents?
2. Is there any restriction on '-msoft-float' ABI definition on 32bit
Linux sys V ABI, 32-bit EABI, 64bit ABI?
3. If PPC linux kernels are built with  '-msoft-float -m64' compiler
option, is it reasonably safe to build the application with the same
options?

Thanks,
Rohit