gdbstub: Allow late attachment

Allow debugging individual processes in multi-process applications by
starting them with export QEMU_GDB=/tmp/qemu-%d.sock,suspend=n.
Currently one would have to attach to every process to ensure the app
makes progress.

In case suspend=n is not specified, the flow remains unchanged. If it
is specified, then accepting the client connection is delegated to a
thread. In the future this machinery may be reused for handling
reconnections and interruptions.

On accepting a connection, the thread schedules gdb_handlesig() on the
first CPU and wakes it up with host_interrupt_signal. Note that the
result of this gdb_handlesig() invocation is handled, as opposed to
many other existing call sites. These other call sites probably need to
be fixed separately.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20250117001542.8290-7-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250207153112.3939799-16-alex.bennee@linaro.org>

1 files changed, 0 insertions, 1 deletions

diff --git a/bsd-user/main.c b/bsd-user/main.c
index b2f6a9be2f..fdb160bed0 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -629,7 +629,6 @@ int main(int argc, char **argv)
 
     if (gdbstub) {
         gdbserver_start(gdbstub, &error_fatal);
-        gdb_handlesig(cpu, 0, NULL, NULL, 0);
     }
     cpu_loop(env);
     /* never exits */