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Julius Werner ffc2260d74 chromeos: vpd: Avoid reading uninitialized VPDs
This patch adds a check to the VPD parsing code to avoid reading the
whole thing if the first byte ('type' of the first VPD entry) is 0x00
or 0xff. These values match the TERMINATOR and IMPLICIT_TERMINATOR types
which should never occur as the first entry, so this usually means that
the VPD FMAP section has simply never been initialized correctly. This
early abort avoids wasting time to read the whole section from SPI flash
(which we'd otherwise have to since we're not going to find a Google VPD
2.0 header either).

BRANCH=None
BUG=None
TEST=Booted Oak, confirmed that VPD read times dropped from 100ms to
1.5ms.

Change-Id: I9fc473e06440aef4e1023238fb9e53d45097ee9d
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 20a726237e03941ad626a6146700170a45ee7720
Original-Change-Id: I09bfec3c24d24214fa4e9180878b58d00454f399
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/322897
Original-Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://review.coreboot.org/13467
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martinroth@google.com>
2016-01-27 16:27:27 +01:00
3rdparty 3rdparty/blobs: Update for latest Carrizo Blobs 2015-12-07 16:10:29 +01:00
Documentation Documentation: Add information about patches from other git repos 2016-01-06 17:41:13 +01:00
payloads payloads: fix dependencies for seabios and filo 2016-01-18 18:57:08 +01:00
src chromeos: vpd: Avoid reading uninitialized VPDs 2016-01-27 16:27:27 +01:00
util chromeos: Add timestamps to measure VPD read times 2016-01-27 16:27:18 +01:00
.clang-format Provide coreboot coding style formalisation file for clang-format 2015-11-10 00:49:03 +01:00
.gitignore .gitignore: add output files for various make targets 2015-11-24 22:35:34 +01:00
.gitmodules submodules: add arm-trusted-firmware third-party repository 2015-06-23 08:20:24 +02:00
.gitreview
COPYING
MAINTAINERS MAINTAINERS: Designate Intel maintainers for FSP 1.0 Baytrail 2015-12-30 20:06:52 +01:00
Makefile Makefile: Correct spelling in help message 2016-01-12 22:19:45 +01:00
Makefile.inc build system: Fix UPDATE_IMAGE 2016-01-27 03:50:29 +01:00
README README: improve description of compiler requirements 2015-07-30 05:11:33 +02:00
toolchain.inc toolchain.inc: Update comments 2016-01-18 03:58:33 +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
------------------

 * make
 * gcc / g++
   Because Linux distribution compilers tend to use lots of patches. coreboot
   does lots of "unusual" things in its build system, some of which break due
   to those patches, sometimes by gcc aborting, sometimes - and that's worse -
   by generating broken object code.
   Two options: use our toolchain (eg. make crosstools-i386) or enable the
   ANY_TOOLCHAIN Kconfig option if you're feeling lucky (no support in this
   case).
 * iasl (for targets with ACPI support)

Optional:

 * doxygen (for generating/viewing documentation)
 * gdb (for better debugging facilities on some targets)
 * ncurses (for 'make menuconfig' and 'make nconfig')
 * 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.