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ARM: list number of HW breakpoints/watchpoints

When starting up, say how many hardware breakpoints and watchpoints
are available on various targets.

This makes it easier to tell GDB how many of those resources exist.
Its remote protocol currently has no way to ask OpenOCD for that
information, so it must configured by hand (or not at all).

Update the docs to mention this; remove obsolete "don't do this" info.
Presentation of GDB setup information is still a mess, but at least
it calls out the three components that need setup.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
tags/v0.4.0-rc1
David Brownell 14 years ago
parent
commit
81aec6be04
4 changed files with 49 additions and 7 deletions
  1. +37
    -7
      doc/openocd.texi
  2. +6
    -0
      src/target/cortex_m3.c
  3. +3
    -0
      src/target/embeddedice.c
  4. +3
    -0
      src/target/xscale.c

+ 37
- 7
doc/openocd.texi View File

@@ -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


+ 6
- 0
src/target/cortex_m3.c View File

@@ -1608,6 +1608,12 @@ static int cortex_m3_examine(struct target *target)

/* Setup DWT */
cortex_m3_dwt_setup(cortex_m3, target);

/* These hardware breakpoints only work for code in flash! */
LOG_INFO("%s: hardware has %d breakpoints, %d watchpoints",
target_name(target),
cortex_m3->fp_num_code,
cortex_m3->dwt_num_comp);
}

return ERROR_OK;


+ 3
- 0
src/target/embeddedice.c View File

@@ -289,6 +289,9 @@ embeddedice_build_reg_cache(struct target *target, struct arm7_9_common *arm7_9)
buf_get_u32(reg_list[EICE_COMMS_CTRL].value, 0, 32));
}

LOG_INFO("%s: hardware has 2 breakpoints or watchpoints",
target_name(target));

return reg_cache;
}



+ 3
- 0
src/target/xscale.c View File

@@ -2970,6 +2970,9 @@ static int xscale_init_arch_info(struct target *target,
xscale->dbr0_used = 0;
xscale->dbr1_used = 0;

LOG_INFO("%s: hardware has 2 breakpoints and 2 watchpoints",
target_name(target));

xscale->arm_bkpt = ARMV5_BKPT(0x0);
xscale->thumb_bkpt = ARMV5_T_BKPT(0x0) & 0xffff;



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