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Paul Menzel cc95f18973 intel/i945/gma: Place GTT below top of memory
Since commit 17fec8a0 [1]

	drm/i915: Use Graphics Base of Stolen Memory on all gen3+

present in the Linux kernel since version 3.12, 3D does not work
anymore [2].

Comparing the graphics registers, in this case that means output of
`intel_reg_dumper`, the vendor Video BIOS is setting the register
PGTBL_CTL/PGETBL_CTL, only documented in the i965 datasheet [3], to
`0x3ffc0001` on a system with 1 GB of RAM, while native graphics init
sets it to `0x3f800001`.

Currently native graphis init sets the GTT right above the base
address of stolen memory. The Video BIOS sets it below the top of
memory.  The Linux Intel driver expects it to be below top of memory, so
do it this way, by setting the address to TOM minus the size of the GTT,
which is hardcoded to 256 KiB.

As `PGETBL_CTL` is zero by default, reading its value in the beginning
is not necessary and is only confusing. Make it clear that the code
calculates the value.

There is still a PTE error reported during boot, but 3D works
with Linux 3.12+ and no user visible problems are shown.

[1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=17fec8a08698bcab98788e1e89f5b8e7502ababd
[2] https://bugs.freedesktop.org/show_bug.cgi?id=79038
[3] https://01.org/linuxgraphics/sites/default/files/documentation/965_g35_vol_1_graphics_core_0.pdf
    Intel ® 965 Express Chipset Family and
      Intel ® G35 Express Chipset Graphics Controller
      Programmer’s Reference Manual
    Volume 1: Graphics Core
    Revision 1.0a

Change-Id: I0a5b04c2c5300f5056cb48075aa5804984bc9948
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Signed-off-by: Francis Rowe <info@gluglug.org.uk>
Reviewed-on: http://review.coreboot.org/5927
Tested-by: build bot (Jenkins)
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>
2014-08-20 09:39:45 +02:00
3rdparty@45f0c04fd7 acpigen: Add acpigen_emit_eisaid. 2014-06-01 01:24:53 +02:00
documentation Documentation: Use correct file name for the build guide in the Makefile 2014-07-04 19:03:10 +02:00
payloads libpayload: usb: Fix several minor USB stack bugs 2014-08-19 23:31:05 +02:00
src intel/i945/gma: Place GTT below top of memory 2014-08-20 09:39:45 +02:00
util board-info: Output errors to stdout like make lint-stable expects 2014-08-18 09:09:22 +02:00
.gitignore .gitignore: add 3 executables that can be built in util/ 2014-08-11 06:26:01 +02:00
.gitmodules gitmodules: Fix 3rdparty updates 2013-06-28 00:56:43 +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 build system: avoid warning about missing .xcompile 2014-07-20 19:51:10 +02:00
Makefile.inc coreboot classes: Add dynamic classes to coreboot 2014-08-11 15:42:20 +02:00
README Update README with newer version of the text from the web page 2011-06-15 10:16:33 +02:00
toolchain.inc coreboot classes: Add dynamic classes to coreboot 2014-08-11 15:42:20 +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.