On Thu, Mar 7, 2013 at 7:56 AM, <Heiko.Papenfuss@xxxxxxxxxxx> wrote: > On 7 March 2013 10:45, <jwakely.gcc@xxxxxxxxx> wrote: >> On 7 March 2013 09:23, <Heiko.Papenfuss@xxxxxxxxxxx> wrote: >> > Hi, >> > >> > I have a question regarding the dependency of libstdc++.so.6 on libc.so.6: >> > >> > If changing the underlying glibc version libc.so.6 is pointing to to a >> > higher version (e.g. from libc-2.4.so to libc-2.7.so), is it expected that >> > the libstdc++.so.6 will still work correctly when used by a program? Or is >> > it necessary to recompile GCC under the new glibc and all our with this >> > new GCC as well? >> >> The libstdc++.so.6 will still work, glibc is also backwards compatible. >> >> You might not be able to use the older GCC with the newer glibc >> headers to compile new programs though, because GCC configures itself >> based on the glibc headers present at the time when GCC is built. If >> you later change glibc then GCC's C++ headers may be incompatible with >> the new glibc headers. If that happens you'd need to rebuild the same >> GCC version against the new glibc. > > How would that become apparent or how could we make sure this is not the > case? In our special case, we have a glibc 2.4 in the system and trying to > use glibc 2.6 instead. Reading the past several posts, I was getting confused. It seems to me you have the reverse scenario from the backwards compatible one. You are attempting to use >2.4 while <=2.4 is on the system. I don't know how you package those updates and/or ensure proper dynamic (?) linkage. > -----Original Message----- > From: Jonathan Wakely [mailto:jwakely.gcc@xxxxxxxxx] > Sent: Donnerstag, 7. März 2013 10:45 > To: Papenfuß Heiko > Cc: gcc-help@xxxxxxxxxxx > Subject: Re: Using libstdc++.so with a newer version of glibc without recompiling > > On 7 March 2013 09:23, <Heiko.Papenfuss@xxxxxxxxxxx> wrote: >> Hi, >> >> I have a question regarding the dependency of libstdc++.so.6 on libc.so.6: >> >> If changing the underlying glibc version libc.so.6 is pointing to to a >> higher version (e.g. from libc-2.4.so to libc-2.7.so), is it expected that >> the libstdc++.so.6 will still work correctly when used by a program? Or is >> it necessary to recompile GCC under the new glibc and all our with this >> new GCC as well? > > The libstdc++.so.6 will still work, glibc is also backwards compatible. > > You might not be able to use the older GCC with the newer glibc > headers to compile new programs though, because GCC configures itself > based on the glibc headers present at the time when GCC is built. If > you later change glibc then GCC's C++ headers may be incompatible with > the new glibc headers. If that happens you'd need to rebuild the same > GCC version against the new glibc.
