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Gabe Black fb8632ab58 oprom: Ensure that mode information is valid before putting it in the tables.
At least when CONFIG_CHROMEOS is turned on, it's possible for
CONFIG_FRAMEBUFFER_KEEP_VESA_MODE to be set but for there not to be any valid
information to put into the framebuffer coreboot table. That means that what's
put in there is junk, probably all zeroes from the uninitialized global
variable the mode information is stored in (mode_info).

When a payload uses libpayload and turns on the coreboot framebuffer console,
that console will attempt to scroll at some point and decrease the cursor's y
coordinate until it is less than the number of rows claimed by the console.
The number of rows is computed by taking the vertical resolution of the
framebuffer and dividing it by the height of the font. Because the mode
information was all zeroes, the coreboot table info is all zeroes, and that
means that the number of rows the console claims is zero. You can't get the
unsigned y coordinate of the cursor to be less than zero, so libpayload gets
stuck in an infinite loop.

The solution this change implements is to add a new function,
vbe_mode_info_valid, which simply returns whether or not mode_info has anything
in it. If not, the framebuffer coreboot table is not created, and libpayload
doesn't get stuck.

Change-Id: I08f3ec628e4453f0cfe9e15c4d8dfd40327f91c9
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: http://review.coreboot.org/1758
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2012-11-12 04:22:34 +01:00
3rdparty@631f0a8209 Updated submodule reference 2012-11-12 04:21:27 +01:00
documentation AMD S3: Add a document about S3 on AMD platform 2012-08-15 23:19:50 +02:00
payloads libpayload: Add an option to skip console initialization on startup. 2012-11-09 22:55:38 +01:00
src oprom: Ensure that mode information is valid before putting it in the tables. 2012-11-12 04:22:34 +01:00
util Utility to dump boot timing table 2012-11-12 03:35:20 +01:00
.gitignore Utility to dump boot timing table 2012-11-12 03:35:20 +01:00
.gitmodules Add 3rdparty as submodule 2012-05-01 00:08:37 +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 Makefile: No need to mkdir when distclean 2012-10-22 21:49:35 +02:00
Makefile.inc mc146818rtc: Remove the hyphen to build on NetBSD and Darwin 2012-11-09 15:26:22 +01:00
README Update README with newer version of the text from the web page 2011-06-15 10:16:33 +02:00

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.