From 19df456a79c912b9e2162ef05c1fd0c02ec7b14a Mon Sep 17 00:00:00 2001 From: Tim Newsome Date: Wed, 5 Oct 2016 07:57:38 -0700 Subject: [PATCH] Perform small writes before sending OK. To speed up downloads, OpenOCD sends gdb OK when a write is received, even before the write has actually occurred. The failure is then returned for the next write. That leads to the following confusing behavior: ``` (gdb) p/x *((int*)0xdeadbeef)=8675309 $2 = 0x845fed (gdb) p/x *((int*)0x80000000)=6874742 Cannot access memory at address 0x80000000 ``` While it's actually the first write that failed. This change hacks around this problem by not sending OK for small writes (len<8) until the write has actually occurred. This does not impact download speed, since during downloads (almost) all writes will have much larger length. Change-Id: I1f8b9bb19b0707487f840df6871e372e4ba228dd Signed-off-by: Tim Newsome Reviewed-on: http://openocd.zylin.com/3803 Tested-by: jenkins Reviewed-by: Tomas Vanek --- src/server/gdb_server.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c index f85fa1bd..7fd579b4 100644 --- a/src/server/gdb_server.c +++ b/src/server/gdb_server.c @@ -1473,6 +1473,10 @@ static int gdb_write_memory_binary_packet(struct connection *connection, uint32_t len = 0; int retval = ERROR_OK; + /* Packets larger than fast_limit bytes will be acknowledged instantly on + * the assumption that we're in a download and it's important to go as fast + * as possible. */ + uint32_t fast_limit = 8; /* skip command character */ packet++; @@ -1493,19 +1497,23 @@ static int gdb_write_memory_binary_packet(struct connection *connection, struct gdb_connection *gdb_connection = connection->priv; - if (gdb_connection->mem_write_error) { + if (gdb_connection->mem_write_error) retval = ERROR_FAIL; - /* now that we have reported the memory write error, we can clear the condition */ - gdb_connection->mem_write_error = false; - } - /* By replying the packet *immediately* GDB will send us a new packet - * while we write the last one to the target. - */ - if (retval == ERROR_OK) - gdb_put_packet(connection, "OK", 2); - else { + if (retval == ERROR_OK) { + if (len >= fast_limit) { + /* By replying the packet *immediately* GDB will send us a new packet + * while we write the last one to the target. + * We only do this for larger writes, so that users who do something like: + * p *((int*)0xdeadbeef)=8675309 + * will get immediate feedback that that write failed. + */ + gdb_put_packet(connection, "OK", 2); + } + } else { retval = gdb_error(connection, retval); + /* now that we have reported the memory write error, we can clear the condition */ + gdb_connection->mem_write_error = false; if (retval != ERROR_OK) return retval; } @@ -1518,6 +1526,15 @@ static int gdb_write_memory_binary_packet(struct connection *connection, gdb_connection->mem_write_error = true; } + if (len < fast_limit) { + if (retval != ERROR_OK) { + gdb_error(connection, retval); + gdb_connection->mem_write_error = false; + } else { + gdb_put_packet(connection, "OK", 2); + } + } + return ERROR_OK; } -- 2.39.5