Hi Shivang,
Sorry for the late reply. The information you provided was very
informative. I'm reviewing and testing against your findings, please
wait a few more while...
Thanks,
Tao Liu
On Fri, Jul 11, 2025 at 3:03 AM shivang upadhyay <shiva...@linux.ibm.com> wrote:
>
> Hi Tao
>
> Thanks for your feedback.
>
> > Agreed, the same code exists in gdb-10.2 and hasn't reported the
> > warning message, so the root cause is somewhere else.
>
> I believe the change was introduced with this gdb patch [1]
> aebb370 ("gdb, solib-svr4: support namespaces in DSO
> iteration") where the call to elf_locate_base was added
> inside the function `svr4_iterate_over_objfiles_in_search_order`.
> which will be called alot of times during the crash initialization.
>
> [1]
> https://github.com/bminor/binutils-gdb/commit/aebb370bae3f511df8afb68a01a79c54e2066650
>
> > I'm not
> > confident that skipping the execution of the code might cause
> > regressions, because there are kernel modules,
>
> I think `elf_locate_base` part should be only for top level
> target. I have tested the module loading functionality with
> my patch applied, and it still successfully handles the `mod
> -S` command. Please let me know if there’s anything else i
> should try or verify.
>
> > which are also elf
> > files, which might need the inspection of the .dynamic section. At
> > least I didn't see any evidence from this patch to address it is safe
> > for the skipping...
>
> I wanted to verify whether the kernel ever includes DT_DEBUG
> information. To investigate this, I printed the data being
> read inside the crash::xfer_partial function (which is
> invoked via elf_locate_base to read from the vmcore).
> However, even when running crash with /proc/kcore, all the
> output data was zero.
>
> So, i believe that kernel will never have this `DT_DEBUG`
> information.
>
> >
> > Thanks,
> > Tao Liu
>
> Thanks
> ~Shivang.
>
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