From: Roque Arcudia Hernandez <roq...@google.com>
In the context of using the remote gdb with multiple
processes/inferiors (multiple cluster machine) a given breakpoint
will target an specific inferior. If needed the remote protocol will
use the packet 'H op thread-id' with op = 'g' to change focus to the
inferior we want to insert/remove the breakpoint to, for instance
'Hgp3.3' and not 'Hcp3.3'.
This is supported by the documentation of the H packets:
> 'H op thread-id'
> Set thread for subsequent operations ('m', 'M', 'g', 'G',
> et.al.). Depending on the operation to be performed, op should be
> 'c' for step and continue operations (note that this is
> deprecated, supporting the 'vCont' command is a better option),
> and 'g' for other operations.
This can also be verified in the GDB source code file gdb/remote.c.
Functions remote_target::insert_breakpoint and
remote_target::remove_breakpoint will eventually call
remote_target::set_general_thread if it needs to change the process
focus and not remote_target::set_continue_thread.
This can be seen around a comment that says:
/* Make sure the remote is pointing at the right process, if
necessary. */
Signed-off-by: Roque Arcudia Hernandez <roq...@google.com>
Signed-off-by: Nabih Estefan <nabiheste...@google.com>
---
gdbstub/gdbstub.c | 4 ++--
gdbstub/internals.h | 13 +++++++++++--
2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 565f6b33a9..0e2e10fbaa 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -1160,7 +1160,7 @@ static void handle_insert_bp(GArray *params, void
*user_ctx)
return;
}
- res = gdb_breakpoint_insert(gdbserver_state.c_cpu,
+ res = gdb_breakpoint_insert(gdbserver_state.g_cpu,
gdb_get_cmd_param(params, 0)->val_ul,
gdb_get_cmd_param(params, 1)->val_ull,
gdb_get_cmd_param(params, 2)->val_ull);
@@ -1184,7 +1184,7 @@ static void handle_remove_bp(GArray *params, void
*user_ctx)
return;
}
- res = gdb_breakpoint_remove(gdbserver_state.c_cpu,
+ res = gdb_breakpoint_remove(gdbserver_state.g_cpu,
gdb_get_cmd_param(params, 0)->val_ul,
gdb_get_cmd_param(params, 1)->val_ull,
gdb_get_cmd_param(params, 2)->val_ull);
diff --git a/gdbstub/internals.h b/gdbstub/internals.h
index bf5a5c6302..e67fb6fe37 100644
--- a/gdbstub/internals.h
+++ b/gdbstub/internals.h
@@ -48,8 +48,17 @@ enum RSState {
typedef struct GDBState {
bool init; /* have we been initialised? */
- CPUState *c_cpu; /* current CPU for step/continue ops */
- CPUState *g_cpu; /* current CPU for other ops */
+ /*
+ * Current CPU for step/continue ops. Updated by the remote packet
+ * 'Hc thread-id'
+ */
+ CPUState *c_cpu;
+ /*
+ * Current CPU for other ops such as memory accesses ('m'/'M'), general
+ * register accesses ('g'/'G'), breakpoint management ('z'/'Z'), etc.
+ * Updated by the remote packet 'Hg thread-id'
+ */
+ CPUState *g_cpu;
CPUState *query_cpu; /* for q{f|s}ThreadInfo */
enum RSState state; /* parsing state */
char line_buf[MAX_PACKET_LENGTH];
--
2.49.0.1015.ga840276032-goog
