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

From: David Howells
Date: Wed Jun 09 2010 - 14:53:11 EST

Reinstate the null behaviour that the in-kernel gdbstub had for the GDB remote
protocol 'p' command (retrieve a single register value) prior to the following

commit 7ca8b9c0dafd1cb36289aa4c92c7beae7adcd34f
Author: David Howells <dhowells@xxxxxxxxxx>
Date: Mon May 24 14:32:54 2010 -0700
Subject: 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

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@xxxxxxxxxx>

arch/frv/kernel/gdb-stub.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/arch/frv/kernel/gdb-stub.c b/arch/frv/kernel/gdb-stub.c
index 84d103c..a4dba6b 100644
--- 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;

+ /* 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];

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