Re: [PATCH] gdb.multi/attach-no-multi-process.exp: Detect no remote non-stop

[Kevin Buettner <kevinb@redhat.com>]

On Fri,  6 Jun 2025 17:29:31 +0100
Pedro Alves <pedro@palves.net> wrote:

> Running gdb.multi/attach-no-multi-process.exp on Cygwin, where
> GDBserver does not support non-stop mode, I see:
> 
>  FAIL: gdb.multi/attach-no-multi-process.exp: target_non_stop=off: info
> threads FAIL: gdb.multi/attach-no-multi-process.exp: target_non_stop=on:
> attach to the program via remote (timeout) FAIL:
> gdb.multi/attach-no-multi-process.exp: target_non_stop=on: info threads
> (timeout)
> 
> Let's ignore the first "info threads" fail.  The timeouts look like
> this:
> 
>  builtin_spawn /home/alves/gdb-cache-cygwin/gdb/../gdbserver/gdbserver
> --once --multi localhost:2346 Listening on port 2346
>  target extended-remote localhost:2346
>  Remote debugging using localhost:2346
>  Non-stop mode requested, but remote does not support non-stop
>  (gdb) gdb_do_cache: can_spawn_for_attach (  )
>  builtin_spawn
> /home/alves/gdb/build-cygwin-testsuite/outputs/gdb.multi/attach-no-multi-process/attach-no-multi-process
> attach 14540 FAIL: gdb.multi/attach-no-multi-process.exp:
> target_non_stop=on: attach to the program via remote (timeout) info
> threads FAIL: gdb.multi/attach-no-multi-process.exp: target_non_stop=on:
> info threads (timeout)
> 
> Note the "Non-stop mode requested, but remote does not support
> non-stop" line.
> 
> The intro to gdb_target_cmd_ext says:
> 
>  # gdb_target_cmd_ext
>  # Send gdb the "target" command.  Returns 0 on success, 1 on failure, 2
> on # unsupported.
> 
> That's perfect here, we can just use gdb_target_cmd_ext instead of
> gdb_target_cmd, and check for 2 (unsupported).  That's what this patch
> does.
> 
> However gdb_target_cmd_ext incorrectly returns 1 instead of 2 for the
> case where the remote target says it does not support non-stop.  That
> is also fixed by this patch.
> 
> With this, we no longer get those timeout fails.  We get instead:
> 
>  target extended-remote localhost:2346
>  Remote debugging using localhost:2346
>  Non-stop mode requested, but remote does not support non-stop
>  (gdb) UNSUPPORTED: gdb.multi/attach-no-multi-process.exp:
> target_non_stop=on: non-stop RSP

LGTM.

Approved-by: Kevin Buettner <kevinb@redhat.com>