[OpenOCD-devel] OpenOCD with GDB client HW RTOS issue

[Daniel G. OS <dgo...@os...>]

Hello,

For the OpenOCD project, I’d like to commit a change to remove the call 
to “rtos_update_threads()” in function gdb_handle_vcont_packet() (file 
gdb_server.c, line 2775), but wanted to get input from the community first.

To provide some environment background, OpenOCD is configured to 
communicate to a GDB client using the GDB remote serial protocol. The 
chip being debugged is an Ampere Computing eMAG 8180 and both 
OpenOCD/GDB are configured SMP multi-core with HW RTOS support enabled. 
The HW RTOS feature allows CPU target selection using the GDB threads 
command.

It’s not clear to me why “rtos_update_threads()” is called here because 
rtos state should already be up-to-date. In addition, this routine calls 
“rtos_free_threadlist()” which wipes out previous thread details such as 
“current_threadid” and “current_thread”. In a GDB multi-cpu (SMP) debug 
environment, resetting current_threadid and current_thread breaks 
functionality on an Ampere Computing eMAG 8180 development platform.

Removing the call fixes the issue I was seeing (current_threadid and 
current_thread values remain intact throughout the call to 
gdb_handle_vcont_packet()).

Specifics below…

File <path>/src/server/gdb_server.c, line 2775
Lines in question:
-start-
/* FIXME: why is this necessary? rtos state should be up-to-date here 
already! */
rtos_update_threads(target);
-end-

Thanks,
Dan Goehring