[PATCH] nptl_db: do not link libthread_db.so with dt-relr

[Carlos O'Donell]

On 6/2/22 10:12, Paul E Murphy via Libc-alpha wrote:
> 
> 
> On 6/1/22 1:56 PM, Adhemerval Zanella wrote:
>> 
>> 
>> On 01/06/2022 14:46, Paul E. Murphy via Libc-alpha wrote:
>>> Should libthread_db.so be dlopen-able by gdb running with a
>>> slightly older glibc without dt-relr support?  If not, I can
>>> rework this to mark these tests unsupported in such cases.
>>> 
>>> ---8<---
>>> 
>>> This may be loaded by a host gdb linked against a libc which does
>>> not support dt-relr.  tst-gdb-pthread-attach{,-static} fails on
>>> powerpc64 whose linker supports dt-relr, but the host libc does
>>> not.
>>> 
>>> Trying host libthread_db library:
>>> .../build/glibc/nptl_db/libthread_db.so.1. dlopen failed:
>>> /lib64/libc.so.6: version `GLIBC_ABI_DT_RELR' not found (required
>>> by .../build/glibc/nptl_db/libthread_db.so.1).
>> 
>> I think it does make sense to disable DT_RELR for libthread_db.so
>> mainly as an improvement for the testsuite regression tests,
>> although I am not sure if the scenario of trying to use a gdb
>> without DT_RELR with a binary that requires DT_RELR would be that
>> usual (it would either require the binary or the gdb to have non
>> standard loader paths).
> 
> It is an unlikely combination, but not so improbable that we've run
> into with two of our CI configurations.
> 
> Is this OK to submit?  I don't think this failure is unique to ppc64.
> However, I am still curious about what, if any, compatibility
> guarantees nptl_db has.
 
Your CI configurations are incorrectly setup.

You must match nptl_db with the runtime.

We only support a matched loader, runtime, and nptl_db.

When we make transitional changes like these we find all the corner cases in our
deployments where we have mismatched the host and test environments.

-- 
Cheers,
Carlos.