This is an automated email from Gerrit.
Antonio Borneo (borneo.anto...@gmail.com) just uploaded a new patch set to
Gerrit, which you can find at http://openocd.zylin.com/4828
-- gerrit
commit 1fde262047cc0df36218bef9fe8f9fe84e959e2d
Author: Antonio Borneo <borneo.anto...@gmail.com>
Date: Thu Jun 7 19:13:09 2018 +0200
gdb_server: add keep-alive during memory read/write
To avoid gdb to timeout, OpenOCD implements a keep-alive mechanism
that consists in sending periodically to gdb empty strings embedded
in the "O" remote reply packet.
The main purpose of "O" packets is to forward in the gdb console
the output of the remote execution; the gdb-remote puts in the "O"
packet the string that gdb will print. It's use is restricted to
few "running/execution" contexts listed in
http://sourceware.org/gdb/onlinedocs/gdb/Stop-Reply-Packets.html
and this currently limits the keep-alive capabilities of OpenOCD.
Long data transfer (memory R/W) can also cause gdb to timeout if
the interface is too slow. In this case the usual keep-alive based
on "O" packet cannot be used and, if used, would trigger a protocol
error that causes the transfer to be dropped.
The slow transfer rate can be simulated by adding some delay in the
main loop of mem_ap_write() and mem_ap_read(), then using the gdb
commands "dump" and "restore".
In the wait loop during a memory R/W, gdb drops any extra character
received from the gdb-remote that is not recognized as a valid
reply to the memory command. Every dropped character re-initializes
the timeout counter and could be used as keep-alive.
From gdb 7.0 (released 2009-10-06), an asynchronous notification
can also be received from gdb-remote during a memory R/W and has
the effect to reset the timeout counter, thus can be used as
keep-alive.
The notification would be treated as "junk" extra characters by any
gdb older than 7.0, being still valid as keep-alive.
Check putpkt_binary() and getpkt_sane() in gdb commit
74531fed1f2d662debc2c209b8b3faddceb55960
Currently, only one notification packet ("Stop") is recognized by
gdb, and gdb documentation reports that notification packets that
are not recognized should be silently dropped.
Use 'set debug remote 1' in gdb to dump the received notifications
and the junk extra characters.
Implement a new log callback that sends a custom "oocd_keepalive"
notification packet when keep_alive() prints an empty string.
Activate this new callback only during memory transfers.
After this commit, the proper calls to keep_alive() have to be
added in the loops that code the memory transfers.
Change-Id: I7681bdd80e86c79130f62ed85c8f6a5ee1478232
Signed-off-by: Antonio Borneo <borneo.anto...@gmail.com>
diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c
index 13e5aca..0ceb032 100644
--- a/src/server/gdb_server.c
+++ b/src/server/gdb_server.c
@@ -1403,11 +1403,6 @@ static int gdb_error(struct connection *connection, int
retval)
return ERROR_OK;
}
-/* We don't have to worry about the default 2 second timeout for GDB packets,
- * because GDB breaks up large memory reads into smaller reads.
- *
- * 8191 bytes by the looks of it. Why 8191 bytes instead of 8192?????
- */
static int gdb_read_memory_packet(struct connection *connection,
char const *packet, int packet_size)
{
@@ -3106,6 +3101,50 @@ static void gdb_log_callback(void *priv, const char
*file, unsigned line,
gdb_output_con(connection, string);
}
+/*
+ * Send custom notification packet as keep-alive during memory read/write.
+ *
+ * From gdb 7.0 (released 2009-10-06) an unknown notification received during
+ * memory read/write would be silently dropped.
+ * Before gdb 7.0 any character, with exclusion of "+-$", would be considered
+ * as junk and ignored.
+ * In both cases the reception will reset the timeout counter in gdb, thus
+ * working as a keep-alive.
+ * Check putpkt_binary() and getpkt_sane() in gdb commit
+ * 74531fed1f2d662debc2c209b8b3faddceb55960
+ *
+ * Enable remote debug in gdb with 'set debug remote 1' to either dump the junk
+ * characters in gdb pre-7.0 and the notification from gdb 7.0.
+ */
+static void gdb_keepalive_callback(void *priv, const char *file, unsigned line,
+ const char *function, const char *string)
+{
+ static unsigned int count;
+ struct connection *connection = priv;
+ struct gdb_connection *gdb_con = connection->priv;
+ int i, len;
+ unsigned int my_checksum = 0;
+ char buf[22];
+
+ /* keep_alive() sends empty strings */
+ if (gdb_con->busy || string[0])
+ return;
+
+ len = sprintf(buf, "%%oocd_keepalive:%2.2x", count);
+ count = (count + 1) & 255;
+ for (i = 1; i < len; i++)
+ my_checksum += buf[i];
+ len += sprintf(buf + len, "#%2.2x", my_checksum & 255);
+
+#ifdef _DEBUG_GDB_IO_
+ LOG_DEBUG("sending packet '%s'", buf);
+#endif
+
+ gdb_con->busy = true;
+ gdb_write(connection, buf, len);
+ gdb_con->busy = false;
+}
+
static void gdb_sig_halted(struct connection *connection)
{
char sig_reply[4];
@@ -3189,10 +3228,14 @@ static int gdb_input_inner(struct connection
*connection)
retval =
gdb_set_register_packet(connection, packet, packet_size);
break;
case 'm':
+
log_add_callback(gdb_keepalive_callback, connection);
retval =
gdb_read_memory_packet(connection, packet, packet_size);
+
log_remove_callback(gdb_keepalive_callback, connection);
break;
case 'M':
+
log_add_callback(gdb_keepalive_callback, connection);
retval =
gdb_write_memory_packet(connection, packet, packet_size);
+
log_remove_callback(gdb_keepalive_callback, connection);
break;
case 'z':
case 'Z':
@@ -3278,9 +3321,9 @@ static int gdb_input_inner(struct connection *connection)
extended_protocol = 0;
break;
case 'X':
+
log_add_callback(gdb_keepalive_callback, connection);
retval =
gdb_write_memory_binary_packet(connection, packet, packet_size);
- if (retval != ERROR_OK)
- return retval;
+
log_remove_callback(gdb_keepalive_callback, connection);
break;
case 'k':
if (extended_protocol != 0) {
--
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