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-rw-r--r--doc/openocd.texi44
1 files changed, 37 insertions, 7 deletions
diff --git a/doc/openocd.texi b/doc/openocd.texi
index ef395ea2..a83c966b 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -6497,6 +6497,21 @@ a bit of googling to find something that fits your requirements.
@cindex GDB
OpenOCD complies with the remote gdbserver protocol, and as such can be used
to debug remote targets.
+Setting up GDB to work with OpenOCD can involve several components:
+
+@itemize
+@item OpenOCD itself may need to be configured. @xref{GDB Configuration}.
+@item GDB itself may need configuration, as shown in this chapter.
+@item If you have a GUI environment like Eclipse,
+that also will probably need to be configured.
+@end itemize
+
+Of course, the version of GDB you use will need to be one which has
+been built to know about the target CPU you're using. It's probably
+part of the tool chain you're using. For example, if you are doing
+cross-development for ARM on an x86 PC, instead of using the native
+x86 @command{gdb} command you might use @command{arm-none-eabi-gdb}
+if that's the tool chain used to compile your code.
@anchor{Connecting to GDB}
@section Connecting to GDB
@@ -6528,19 +6543,34 @@ session.
To list the available OpenOCD commands type @command{monitor help} on the
GDB command line.
+@section Configuring GDB for OpenOCD
+
OpenOCD supports the gdb @option{qSupported} packet, this enables information
to be sent by the GDB remote server (i.e. OpenOCD) to GDB. Typical information includes
packet size and the device's memory map.
+You do not need to configure the packet size by hand,
+and the relevant parts of the memory map should be automatically
+set up when you declare (NOR) flash banks.
+
+However, there are other things which GDB can't currently query.
+You may need to set those up by hand.
+As OpenOCD starts up, you will often see a line reporting
+something like:
-Previous versions of OpenOCD required the following GDB options to increase
-the packet size and speed up GDB communication:
@example
-set remote memory-write-packet-size 1024
-set remote memory-write-packet-size fixed
-set remote memory-read-packet-size 1024
-set remote memory-read-packet-size fixed
+Info : lm3s.cpu: hardware has 6 breakpoints, 4 watchpoints
@end example
-This is now handled in the @option{qSupported} PacketSize and should not be required.
+
+You can pass that information to GDB with these commands:
+
+@example
+set remote hardware-breakpoint-limit 6
+set remote hardware-watchpoint-limit 4
+@end example
+
+With that particular hardware (Cortex-M3) the hardware breakpoints
+only work for code running from flash memory. Most other ARM systems
+do not have such restrictions.
@section Programming using GDB
@cindex Programming using GDB