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Julius Werner e7b079f4b6 rk3288: Add early SRAM mapping
Solving the DACR bug will mean that XN bits suddenly become enforced on
non-LPAE systems, and we will no longer be able to execute out of a
region mapped DCACHE_OFF. When we enable the MMU in romstage we are
still executing out of SRAM, so we would instantly kill ourselves.

Solve this issue by enabling the MMU earlier (in the bootblock) and
mapping the SRAM regions as DCACHE_WRITETHROUGH. They should really be
DCACHE_WRITEBACK, but it looks like there might be hardware limitations
in the Cortex-A12 cache architecture that prevent us from doing so.
Write-through mappings are equivalent to normal non-cacheable on the A12
anyway, and by using this attribute we don't need to introduce a new
DCACHE_OFF_BUT_WITHOUT_XN_BIT type in our API. (Also, using normal
non-cacheable might still have a slight speed advantage over strongly
ordered since it should fetch whole cache lines at once if the processor
finds enough accesses it can combine.)

CQ-DEPEND=CL:223783
BUG=chrome-os-partner:32118
TEST=None (depends on follow-up CL)

Change-Id: I53e827d95acc2db909f1251de78d65e295eceaa7
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/223782
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
2014-10-17 21:54:36 +00:00
configs cosmos: add template files for libpayload 2014-10-15 18:23:26 +00:00
documentation sconfig: rename lapic_cluster -> cpu_cluster 2013-02-14 07:07:20 +01:00
payloads libpayload: normalize board configurations 2014-10-17 03:24:54 +00:00
src rk3288: Add early SRAM mapping 2014-10-17 21:54:36 +00:00
util timestamp: Add bootblock start and end to timestamp constants 2014-10-17 05:52:39 +00:00
.gitignore rmodules: add support for rmodtool 2014-03-31 22:25:57 +00:00
COMMIT-QUEUE.ini COMMIT-QUEUE.ini: Add documentation. 2013-11-01 14:08:42 +00:00
COPYING update license template. 2006-08-12 22:03:36 +00:00
Makefile Makefile: Change $(generic-deps) to order-only prerequisite 2014-10-04 03:10:51 +00:00
Makefile.inc Change GDB_DEBUG to SOURCE_DEBUG 2014-10-08 05:07:21 +00:00
PRESUBMIT.cfg chromeos: Add PRESUBMIT.cfg 2013-05-01 14:31:10 -07:00
README Update README with newer version of the text from the web page 2011-06-15 10:16:33 +02:00
toolchain.inc arch/mips: Add base MIPS architecture support 2014-09-01 11:05:57 +00:00

-------------------------------------------------------------------------------
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.