Building older GLIBC on newer system

Question

I have a question and I hope some guru here could help me out :) My goal is simple : (GOAL1) build a older glibc on a newer system and (GOAL2) build old software that can run on older glibc. I am on gcc4.9, glibc2.19, amd64 system. I did compile glibc2.14 and gcc4.7.3 on my system.

(convention : /path/to/libc2.14_dir = $LIBC214, /path/to/gcc4.7.3 = $GCC473)

I am trying to compile bash4.2.53 ( and other softwares coreutil, binutil, qt3.3...) using newly built glibc2.14. My configure and make looks like this : ( I am being in object/build directory )

$ cd /path/to/build/bash-4.2.53
$ CC=$GCC473/bin/gcc CXX=$GCC473/bin/g++ CPP=$GCC473/bin/cpp \
   /path/to/source/bash-4.2.53/configure \
   --prefix=/path/to/installation/bash-4.2.53
$ make all V=1 \
   CFLAGS="-Wl,--rpath=$LIBC214/lib -Wl,--dynamic-linker=$LIBC214/lib/ld-linux-x86-64.so.2" \
   CPPFLAGS="-Wl,--rpath=$LIBC214/lib -Wl,--dynamic-linker=$LIBC214/lib/ld-linux-x86-64.so.2" \
   CXXFLAGS="-Wl,--rpath=$LIBC214/lib -Wl,--dynamic-linker=$LIBC214/lib/ld-linux-x86-64.so.2" 

When make is done in bash4.2.53 build (object) directory, I tried 2 scenarios :

SCENARIO1. Use system's libc2.19

$ ldd ./bash
   linux-vdso.so.1 (0x00007ffe677c3000)
   libtinfo.so.5 => $MY_PREBUILT_NCURSE/lib/libtinfo.so.5 (0x00007f5d108e3000)
   libdl.so.2 => $LIBC214/lib/libdl.so.2 (0x00007f5d106df000)
   libc.so.6 => $LIBC214/lib/libc.so.6 (0x00007f5d10354000)
   $LIBC214/lib/ld-linux-x86-64.so.2 => /lib64/ld-linux-x86-64.so.2 (0x00007f5d10b0a000)

This line is weird :$LIBC214/lib/ld-linux-x86-64.so.2 => /lib64/ld-linux-x86-64.so.2 (0x00007f5d10b0a000)

$ $LIBC214/bin/ldd ./bash
   not a dynamic executable

SCENARIO2. Add $LIBC214/bin to my PATH, $LIBC214/lib to my LD_LIBRARY_PATH

$ ldd ./bash
/bin/bash: $LIBC214/lib/libc.so.6: version `GLIBC_2.15' not found (required by /bin/bash)
$ export SHELL=$PWD/bash
$ ldd --version
/bin/bash: $LIBC214/lib/libc.so.6: version `GLIBC_2.15' not found (required by /bin/bash)
$ ldd ./bash
/bin/bash: $LIBC214/lib/libc.so.6: version `GLIBC_2.15' not found (required by /bin/bash)

As far as I can tell, SCENARIO2 is the right way to run commands. My assumption is that I built glibc2.14 wrongly, that it uses /bin/bash which in turn uses glibc2.19. I am not really sure.

My question:

1. Could you please explain for me the weird line above and the following line that out put not a dynamic executable?

2. Could you share me your steps to properly build glibc (GOAL1) and build software using that glibc (GOAL2) ?

3. What could I do next to solve 2 above scenario?

Thank you.

Answer 1

when you link ELFs, the absolute path to the ldso is hardcoded in it. if you want to use a different one, you can use the -Wl,--dynamic-linker=/path/to/ldso flag to override it. this path is absolute though, so if you try to move your local glibc somewhere else, the ELFs you linked will fail to execute (with errors like no such file). there's no way around this as the system, by design, must have an absolute path in it to the interpreter.

the reason you get weird not a dynamic executable output is that ldd works by actually executing the target ELF and extracting (via debug hooks) the libraries that get loaded. so when you attempt to use a diff ldd like that, glibc gets confused. if you want a stable dependency lister, you might consider something like lddtree from the pax-utils project (most distros have this bundled nowadays). or run readelf -d on the file directly and look at all the DT_NEEDED entries.

trying to build & maintain your own toolchain (glibc, gcc, etc...) is a huge hassle. unless you want to dedicate a lot of time to this, you really should use a project like crosstool-ng to manage it for you. that will allow you to build a full toolchain using an older glibc, and then you can use that to build whatever random packages you like.

if you really really want to spend time doing this all by hand, you should refer to the glibc wiki for building your own glibc and then linking apps against that glibc.