On Fri, Jan 05, 2018 at 06:33:50PM +0100, Jakub Jelinek wrote: > On Thu, Jan 04, 2018 at 06:05:55PM -0500, Michael Meissner wrote: > > This patch is the beginning step to switching the PowerPC long double > > support > > from IBM extended double to IEEE 128-bit floating point on PowerPC servers. > > It > > will be necessary to have this patch or a similar patch to allow the GLIBC > > team > > to begin their modifications in GLIBC 2.28, so that by the time GCC 9 comes > > out, we can decide to switch the default. It is likely, the default will > > only > > be switched on the 64-bit little endian PowerPC systems, when a distribution > > goes through a major level, such that they can contemplate major changes. > > When you're mentioning multilibs, does that mean that we'll have two ABI > incompatible libgcc.so.* libraries, two ABI incompatible libstdc++.so.* > libraries etc.? Just one or 2 libc.so.*/libm.so.*? > > At least when doing the long double format double to doubledouble transition > (or on other targets to quad) last time we've managed to make it ABI > compatible.
We are hoping that it eventually will not need multilibs. But during the initial development, it is likely that we will need to use multilibs. That is what the patch is for -- to allow building the compiler that supports multilibs, but it is not on by default. Part of the issue is GCC and GLIBC rev on different cycles and are done by different people. I have to guess what GLIBC will need, so that we have the GLIBC solution by the time GCC 9 is ready. -- Michael Meissner, IBM IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA email: meiss...@linux.vnet.ibm.com, phone: +1 (978) 899-4797
