RE: [PATCH 1/2] gdb, multi-target: pass a target argument to prune_threads

["Aktemur, Tankut Baris" <tankut.baris.aktemur@intel.com>]

Hi Andrew,

On Friday, April 17, 2026 5:35 PM, Simon Marchi wrote:
> On 4/17/26 11:16 AM, Andrew Burgess wrote:
> > Tankut Baris Aktemur <tankut.baris.aktemur@intel.com> writes:
> >
> >> From the way 'prune_threads' is used, it is designed to delete the
> >> threads of the current target.  So, while iterating the threads,
> >> ignore those that do not belong to the current target.
> >
> > I'm not saying that you're wrong, but could you expand on this, maybe
> > giving some examples of how it's used and why that suggests it should be
> > a per- target operation.
> >
> > Did the current code cause some problems?  Is there scope for adding a
> > test maybe?
> >
> > FWIW: I think this change is probably OK, but the commit message seems a
> > little light on detail for my taste.
> >
> > Thanks,
> > Andrew
> 
> I'm not against having more details, but the fact that prune_threads is
> called from the various targets' update_thread_list methods (or similar)
> is a good clue.  In a multi-target scenario, as the  target updates the
> threads it is responsible for, it should not start messing with threads
> of other targets.

What Simon wrote here is the motivation of the patch.  I tried to
state this in the commit message, but I admit it wasn't so clear.

The concrete problem that led to the patch is the following:
Intel's downstream debugger uses two targets (native and remote)
in non-stop and all-stop mode.  (This combination is not supported
in upstream GDB but there are additional patches in Intel's branch
to enable non-stop + all-stop configuration.)
When there is a stop event coming from the native target, GDB enters
stop_all_threads, where it attempts to update the thread list of each
target.  However, the other target (i.e. remote) is in all-stop mode
and it cannot respond to the thread_alive request made in prune_threads,
leading to an error.

Regards,
-Baris


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