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Julius Werner 50a81748fd libpayload: Add remote GDB support
This patch adds the ability to attach a GDB host through the UART to a
running payload. Libpayload implements a small stub that can parse and
respond to the GDB remote protocol and provide the required primitives
(reading/writing registers/memory, etc.) to allow GDB to control
execution.

The goal of this implementation is to be as small and uninvasive as
possible. It implements only the minimum amount of primitives required,
and relies on GDB's impressive workaround capabilities (such as
emulating breakpoints by temporarily replacing instructions) for the
more complicated features. This way, a relatively tiny amount of code on
the firmware side opens a vast range of capabilities to the user, not
just in debugging but also in remote-controlling the firmware to change
its behavior (e.g. through GDBs ability to modify variables and call
functions).

By default, a system with the REMOTEGDB Kconfig will only trap into GDB
when executing halt() (including the calls from die_if(), assert(), and
exception handlers). In addition, payloads can manually call gdb_enter()
if desired. It will print a final "Ready for GDB connection." on the
serial, detach the normal serial output driver and wait for the commands
that GDB starts sending on attach.

Based on original implementation by Gabe Black <gabeblack@chromium.org>.

BUG=chrome-os-partner:18390
TEST=Boot a GDB enabled image in recovery mode (or get it to hit a
halt()), close your terminal, execute '<toolchain>-gdb --symbols
/build/<board>/firmware/depthcharge_gdb/depthcharge.elf --directory
~/trunk/src/third_party/coreboot/payloads/libpayload --directory
~/trunk/src/platform/depthcharge --directory
~/trunk/src/platform/vboot_reference --ex "target remote
<cpu_uart_pty>"' and behold the magic.
(You can also SIGSTOP your terminal's parent shell and the terminal
itself, and SIGCONT them in reverse order after GDB exits. More
convenient wrapper tools to do all this automatically coming soon.)

Original-Change-Id: Ib440d1804126cdfdac4a8801f5015b4487e25269
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/202563
Original-Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
(cherry picked from commit 9c4a642c7be2faf122fef39bdfaddd64aec68b77)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I9238b4eb19d3ab2c98e4e1c5946cd7d252ca3c3b
Reviewed-on: http://review.coreboot.org/8119
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-01-09 07:06:51 +01:00
3rdparty@a8b0c52850 3rdparty: Update to latest commit in blobs repository 2014-12-28 16:04:03 +01:00
documentation Doxygen: add a "simple" output config and make target 2015-01-08 21:59:17 +01:00
payloads libpayload: Add remote GDB support 2015-01-09 07:06:51 +01:00
src storm: Reserve memory from 0x4000_0000-0x414f_ffff 2015-01-09 06:21:08 +01:00
util inteltool: add `-s` to dump spi bar and bios_cntl registers 2015-01-08 17:49:58 +01:00
.gitignore .gitignore: add the doxygen directory. 2014-12-14 23:30:45 +01:00
.gitmodules nvidia/cbootimage: avoid upstream's build system 2014-10-02 10:26:58 +02:00
.gitreview add .gitreview 2012-11-01 23:13:39 +01:00
COPYING update license template. 2006-08-12 22:03:36 +00:00
Makefile Doxygen: add a "simple" output config and make target 2015-01-08 21:59:17 +01:00
Makefile.inc intel: Fix UPDATE-FIT step in build 2014-12-28 19:58:59 +01:00
README Update README with newer version of the text from the web page 2011-06-15 10:16:33 +02:00
toolchain.inc Add UCB RISCV support for architecture, soc, and emulation mainboard.. 2014-12-01 19:06:43 +01:00

README

-------------------------------------------------------------------------------
coreboot README
-------------------------------------------------------------------------------

coreboot is a Free Software project aimed at replacing the proprietary BIOS
(firmware) found in most computers.  coreboot performs a little bit of
hardware initialization and then executes additional boot logic, called a
payload.

With the separation of hardware initialization and later boot logic,
coreboot can scale from specialized applications that run directly
firmware, run operating systems in flash, load custom
bootloaders, or implement firmware standards, like PC BIOS services or
UEFI. This allows for systems to only include the features necessary
in the target application, reducing the amount of code and flash space
required.

coreboot was formerly known as LinuxBIOS.


Payloads
--------

After the basic initialization of the hardware has been performed, any
desired "payload" can be started by coreboot.

See http://www.coreboot.org/Payloads for a list of supported payloads.


Supported Hardware
------------------

coreboot supports a wide range of chipsets, devices, and mainboards.

For details please consult:

 * http://www.coreboot.org/Supported_Motherboards
 * http://www.coreboot.org/Supported_Chipsets_and_Devices


Build Requirements
------------------

 * gcc / g++
 * make

Optional:

 * doxygen (for generating/viewing documentation)
 * iasl (for targets with ACPI support)
 * gdb (for better debugging facilities on some targets)
 * ncurses (for 'make menuconfig')
 * flex and bison (for regenerating parsers)


Building coreboot
-----------------

Please consult http://www.coreboot.org/Build_HOWTO for details.


Testing coreboot Without Modifying Your Hardware
------------------------------------------------

If you want to test coreboot without any risks before you really decide
to use it on your hardware, you can use the QEMU system emulator to run
coreboot virtually in QEMU.

Please see http://www.coreboot.org/QEMU for details.


Website and Mailing List
------------------------

Further details on the project, a FAQ, many HOWTOs, news, development
guidelines and more can be found on the coreboot website:

  http://www.coreboot.org

You can contact us directly on the coreboot mailing list:

  http://www.coreboot.org/Mailinglist


Copyright and License
---------------------

The copyright on coreboot is owned by quite a large number of individual
developers and companies. Please check the individual source files for details.

coreboot is licensed under the terms of the GNU General Public License (GPL).
Some files are licensed under the "GPL (version 2, or any later version)",
and some files are licensed under the "GPL, version 2". For some parts, which
were derived from other projects, other (GPL-compatible) licenses may apply.
Please check the individual source files for details.

This makes the resulting coreboot images licensed under the GPL, version 2.