Re: librt and libpthread in alternate prefix

[Poor Yorick <org dot sourceware dot libchelp at pooryorick dot com>]

Mike Frysinger wrote:
> On Monday 04 May 2009 13:59:39 Poor Yorick wrote:
>> Built and installed glibc-2.9 in an alternate location.
>> <prefix>/bin/ldconfig shows:
>>
>>         libpthread.so.0 (libc6, hwcap: 0x8000000000000000, OS ABI: Linux
>> 2.4.20) => /lib/tls/libpthread.so.0
>>         libpthread.so.0 (libc6, hwcap: 0x0008000000000000, OS ABI: Linux
>> 2.4.1) => /lib/i686/libpthread.so.0
>>         libpthread.so.0 (libc6, OS ABI: Linux 2.2.5) =>
>> /lib/libpthread.so.0 libpthread.so.0 (libc6, OS ABI: Linux 2.0.0) =>
>> <prefix>/glibc-2.9/lib/libpthread.so.0
>>
>>
>> Programs that link to /alternate/glibc-2.9/lib/librt.so.1 end up linked to
>> /lib/tls/libpthread.so.0 instead of to
>> /alternate/libc-2.9/lib/libpthread.so.0, presumably because the OS ABI is
>> greater, but this combination causes executables to segfault.
>
> you must either use all of the new glibc or none of it.  mixing glibc libs is
> not supported in any way and will most likely crash.
>
>> I thought the workaround might be to embed an RPATH/RUNPATH in librt.so so
>> that it always finds its sibling libpthread.  I've tried getting paths
>> embedded into libc shared objects before, but the builds never completed
>> succesfully.  Any hints on the right way to do this?
>
> no, using runpaths isnt going to matter because you need to execute the new
> ldso as well.  please review the glibc wiki as there are pages covering how to
> do this.
> -mike

But I am using the new ldso, and using all of the new glibc is precisely what
I'm trying to do.  It's just that the new ldso insists on linking against
another libpthread on the system.  In the output above, you'll see that the new
pthread is in the new ld.so.cache, but there are also other libpthreads listed
there which have a higher OS ABI.  I need the new libc to use its own
libpthread, but that isn't happening, and I'm not sure how to make it happen,
given that I do need the new ld.so.cache to also index a few other paths (/lib,
/usr/lib).  A cursory search through the wiki didn't turn up a page that deals
with this situation.  A pointer would be much appreciated.

--
Yorick