From e4125d136c72b1225c4547e670db102f88cf6efc Mon Sep 17 00:00:00 2001 From: Anton Kolesov Date: Wed, 22 Jan 2014 20:18:56 +0400 Subject: [PATCH] gdb_server: Fix confusing warning when entering noack mode Comment in gdb_server code mistakenly attributed constant warnings about unexpected acknowledgement to the ACK packet sent by GDB when establishing connection. However that is not the case, OpenOCD gdb_server is handling this packet correctly without an warnings. This warning instead was caused by the ACK packet which GDB sends right after going into noack mode. Because OpenOCD gdb_server is already in noack mode at this state, it emits warning about it. This is a documented GDB behaviour (https://sourceware.org/gdb/onlinedocs/gdb/Packet-Acknowledgment.html) so there is no reason to scare users with warnings in this case. This patch basically introduces two-level noack mode: after receiving QStartNoAckMode gdb_server will set noack_mode to 1, then it will receive this last ACK packet, but instead of printing a warning, noack_mode will be increased to 2. Should there be any other ACK packets after that, they will be properly reported by warning. All other code that relies on noack_mode checks it for "!= 0", so there will be no difference if it is 1 or 2. Change-Id: I0e9c57fd93293bfe010390db2f3f161528b11d86 Signed-off-by: Anton Kolesov Reviewed-on: http://openocd.zylin.com/1895 Tested-by: jenkins Reviewed-by: Spencer Oliver --- src/server/gdb_server.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c index ea8211408..7bf7319c5 100644 --- a/src/server/gdb_server.c +++ b/src/server/gdb_server.c @@ -617,11 +617,21 @@ static int gdb_get_packet_inner(struct connection *connection, case '$': break; case '+': - /* gdb sends a dummy ack '+' at every remote connect - see - * remote_start_remote (remote.c) - * in case anyone tries to debug why they receive this - * warning every time */ - LOG_WARNING("acknowledgment received, but no packet pending"); + /* According to the GDB documentation + * (https://sourceware.org/gdb/onlinedocs/gdb/Packet-Acknowledgment.html): + * "gdb sends a final `+` acknowledgment of the stub's `OK` + * response, which can be safely ignored by the stub." + * However OpenOCD server already is in noack mode at this + * point and instead of ignoring this it was emitting a + * warning. This code makes server ignore the first ACK + * that will be received after going into noack mode, + * warning only about subsequent ACK's. */ + if (gdb_con->noack_mode > 1) { + LOG_WARNING("acknowledgment received, but no packet pending"); + } else { + LOG_DEBUG("Received first acknowledgment after entering noack mode. Ignoring it."); + gdb_con->noack_mode = 2; + } break; case '-': LOG_WARNING("negative acknowledgment, but no packet pending");