gdbstub: add multiprocess support to 'sC' packets

Change the sC packet handling to support the multiprocess extension.
Instead of returning the first thread, we return the first thread of the
current process.

Signed-off-by: Luc Michel <luc.michel@greensocs.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20181207090135.7651-7-luc.michel@greensocs.com
[PMM: corrected checkpatch comment style nit]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 9 insertions, 3 deletions

diff --git a/gdbstub.c b/gdbstub.c
index 09114ea776..1ba7aa6a28 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -1554,9 +1554,15 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
             put_packet(s, "OK");
             break;
         } else if (strcmp(p,"C") == 0) {
-            /* "Current thread" remains vague in the spec, so always return
-             *  the first CPU (gdb returns the first thread). */
-            put_packet(s, "QC1");
+            /*
+             * "Current thread" remains vague in the spec, so always return
+             * the first thread of the current process (gdb returns the
+             * first thread).
+             */
+            cpu = get_first_cpu_in_process(s, gdb_get_cpu_process(s, s->g_cpu));
+            snprintf(buf, sizeof(buf), "QC%s",
+                     gdb_fmt_thread_id(s, cpu, thread_id, sizeof(thread_id)));
+            put_packet(s, buf);
             break;
         } else if (strcmp(p,"fThreadInfo") == 0) {
             s->query_cpu = first_cpu;