[gdbstub] redirecting qemu console output to a debugger

[Sid Manning]

Currently when I attach a debugger (lldb) to my qemu session all of the output 
goes to the shell running qemu not to the debugger.  Fixing this meant that I 
needed to point the semi-hosting output to the gdb chardev.  I started qemu 
like this:

-s -S -semihosting-config target=auto,chardev=ch0 -chardev gdb,id=ch0

But this failed with the error:
-chardev gdb,id=ch0: 'gdb' is not a valid char driver name

In order to fix this I needed to change the stub's chardev from internal to 
external:

@@ -3446,7 +3446,7 @@ static void char_gdb_class_init(ObjectClass *oc, void 
*data)
 {
     ChardevClass *cc = CHARDEV_CLASS(oc);
 
-    cc->internal = true;
+    cc->internal = false;
     cc->open = gdb_monitor_open;
     cc->chr_write = gdb_monitor_write;
 }

Afterward console output was routed to the debugger.  This is the only chardev 
device I found that is marked as internal so I suspect this is the wrong thing 
to do.  What is the proper way to redirect output from qemu to the debugger?

Thanks,