Add a gdb script with two helper functions which use the new
pbl_barebox_break symbol to calculate the current barebox load address
on the device and loads a barebox ELF file to this address.
Signed-off-by: Rouven Czerwinski <r.czerwinski@xxxxxxxxxxxxxx>
---
Documentation/user/debugging.rst | 21 +++++++++++
Documentation/user/user-manual.rst | 1 +
common/Kconfig | 9 +++++
scripts/gdb/helper.py | 60 ++++++++++++++++++++++++++++++
4 files changed, 91 insertions(+)
create mode 100644 Documentation/user/debugging.rst
create mode 100644 scripts/gdb/helper.py
diff --git a/Documentation/user/debugging.rst b/Documentation/user/debugging.rst
new file mode 100644
index 0000000000..15cb439043
--- /dev/null
+++ b/Documentation/user/debugging.rst
@@ -0,0 +1,21 @@
+Debugging with OpenOCD
+======================
+
+Barebox can be configured to break on prebootloader and main barebox entry. This
+breakpoint can not be resumed and will stop the board to allow the user to
+attach a JTAG debugger with OpenOCD. Additionally, barebox provides helper
+scripts to load the symbols from the ELF binaries.
+The python scripts require `pyelftools`.
+To load the scripts into your gdb session, run the following command in the
+barebox directory:
+
+.. code-block:: none
+
+ (gdb) source scripts/gdb/helper.py
+
+This makes two new commands available in gdb, `bb-load-symbols` and
+`bb-skip-break`. `bb-load-symbols` can load either the main `barebox` file or
+one of the .pbl files in the image directories. The board needs to be stopped in
+either the prebootloader or main barebox breakpoint, and gdb needs to be
+connected to OpenOCD. To continue booting the board, `bb-skip-break` jumps over
+the breakpoint and continues the barebox execution.
diff --git a/Documentation/user/user-manual.rst b/Documentation/user/user-manual.rst
index 516b760b1b..f04981c3f0 100644
--- a/Documentation/user/user-manual.rst
+++ b/Documentation/user/user-manual.rst
@@ -33,6 +33,7 @@ Contents:
system-reset
state
random
+ debugging
* :ref:`search`
* :ref:`genindex`
diff --git a/common/Kconfig b/common/Kconfig
index 4124857a0a..c766e1ef64 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -1252,6 +1252,15 @@ config PBL_BREAK
If this enabled, barebox will be compiled with BKPT instruction
on early pbl init. This option be used only with JTAG debugger!
+config GDB_SCRIPTS
+ bool "Provide GDB scripts for barebox debugging"
+ help
+ This creates the required links to GDB helper scripts in the
+ build directory. If you load barebox into gdb, the helper
+ scripts will be automatically imported by gdb as well, and
+ additional functions are available to analyze a Linux kernel
+ instance.
+
endmenu
config HAS_DEBUG_LL
diff --git a/scripts/gdb/helper.py b/scripts/gdb/helper.py
new file mode 100644
index 0000000000..4041789890
--- /dev/null
+++ b/scripts/gdb/helper.py
@@ -0,0 +1,60 @@
+#!/usr/bin/env python
+
+import gdb
+
+try:
+ from elftools.elf.elffile import ELFFile
+ from elftools.common.exceptions import ELFError
+except ImportError:
+ gdb.write("The barebox helper requires pyelftools\n", gdb.STDERR)
+ exit(1)
+
+
+class BBSymbols(gdb.Command):
+
+ def __init__(self):
+ super(BBSymbols, self).__init__("bb-load-symbols", gdb.COMMAND_FILES,
+ gdb.COMPLETE_FILENAME)
+
+ def invoke(self, argument, from_tty):
+ path = argument
+ f = open(path, 'rb')
+
+ try:
+ elf = ELFFile(f)
+ except ELFError:
+ gdb.write("Selected file is not an ELF file\n", gdb.STDERR)
+ return
+
+ section = elf.get_section_by_name(".symtab")
+ if section is None:
+ gdb.write("Section .symtab not found\n", gdb.STDERR)
+ return
+ symbol = section.get_symbol_by_name("pbl_barebox_break")
+ if not symbol:
+ gdb.write("Symbol pbl_barebox_break in section {} in file {} not found\n"
+ .format(section.name, self.path), gdb.STDERR)
+ return
+ symbol = symbol[0]
+ pc = gdb.parse_and_eval("$pc")
+ symbol_address = int(symbol.entry.st_value)
+ address = int(pc) - symbol_address + 1
+ gdb.execute("symbol-file")
+ gdb.execute("add-symbol-file {} {}".format(path, address))
+
+
+BBSymbols()
+
+
+class BBSkip(gdb.Command):
+
+ def __init__(self):
+ super(BBSkip, self).__init__("bb-skip-break", gdb.COMMAND_BREAKPOINTS)
+
+ def invoke(self, arg, from_tty):
+ pc = gdb.parse_and_eval("$pc")
+ nop_address = int(pc) + 2
+ gdb.execute("jump *{}".format(nop_address))
+
+
+BBSkip()
--
2.21.0
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