FRV: Reinstate null behaviour for the GDB remote protocol 'p' command

Reinstate the null behaviour that the in-kernel gdbstub had for the GDB
remote protocol 'p' command (retrieve a single register value) prior to
commit 7ca8b9c0dafd ("frv: extend gdbstub to support more features of
gdb").

Before that, the 'p' command just returned an empty reply, which causes
gdb to then go and use the 'g' command.  However, since that commit, the
'p' command returns an error string, which causes gdb to abort its
connection to the target.

Not all gdb versions are affected, some use try 'g' first, and if that
works, don't bother with 'p', and so don't see the error.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/frv/kernel/gdb-stub.c b/arch/frv/kernel/gdb-stub.c
index 84d103c33c9c4356220725a853405ccf15ab8870..a4dba6b20bd0b8f4e2cd9582bd97c9a39a8453b7 100644 (file)
--- a/arch/frv/kernel/gdb-stub.c
+++ b/arch/frv/kernel/gdb-stub.c
@@ -1789,6 +1789,12 @@ void gdbstub(int sigval)
                        flush_cache = 1;
                        break;
 
+                       /* pNN: Read value of reg N and return it */
+               case 'p':
+                       /* return no value, indicating that we don't support
+                        * this command and that gdb should use 'g' instead */
+                       break;
+
                        /* PNN,=RRRRRRRR: Write value R to reg N return OK */
                case 'P':
                        ptr = &input_buffer[1];