Files
system76-coreboot/payloads/libpayload
Andrew Bresticker 44c5105890 libpayload: mips: Do not set C0_EBase_WG
The WG (write gate) bit in C0_EBase allows the upper two bits of
the exception base address to be set to something other than 2'b10,
thus allowing it to be relocated out of the traditional KSEG{0,1}
range.  Since we're not using the segmentation features introduced
by EVA to relocate the unmapped segments, the exception vectors
should remain in KSEG0.  Don't set the WG bit so that the upper
two bits of the exception base (2'b00, because of the identity
mapping) are ignored and we execute the exception vectors out of
KSEG0.

BUG=chrome-os-partner:36258
BRANCH=none
TEST=Build and boot on Pistachio.

Change-Id: Ie8b4eb6e41a328e7055736c9e3f6ff5ec83b9e13
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: d5b002f5ae71c7729e467d4fe3fd8db187e15dea
Original-Change-Id: Id8b930db1e7a68f52dd61be4dfa9edaee2bebf7d
Original-Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/246697
Original-Reviewed-by: Ionela Voinescu <ionela.voinescu@imgtec.com>
Original-Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Tested-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Commit-Queue: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: http://review.coreboot.org/9822
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-04-21 08:13:52 +02:00
..
2012-04-04 00:40:31 +02:00

-------------------------------------------------------------------------------
libpayload README
-------------------------------------------------------------------------------

libpayload is a minimal library to support standalone payloads
that can be booted with firmware like coreboot. It handles the setup
code, and provides common C library symbols such as malloc() and printf().

Note: This is _not_ a standard library for use with an operating system,
rather it's only useful for coreboot payload development!
See http://coreboot.org for details on coreboot.


Installation
------------

 $ git clone http://review.coreboot.org/p/coreboot.git

 $ cd coreboot/payloads/libpayload

 $ make menuconfig

 $ make

 $ sudo make install (optional, will install into /opt per default)

As libpayload is for 32bit x86 systems only, you might have to install the
32bit libgcc version, otherwise your payloads will fail to compile.
On Debian systems you'd do 'apt-get install gcc-multilib' for example.


Usage
-----

Here's an example of a very simple payload (hello.c) and how to build it:

 #include <libpayload.h>

 int main(void)
 {
     printf("Hello, world!\n");
     return 0;
 }

Building the payload using the 'lpgcc' compiler wrapper:

 $ lpgcc -o hello.elf hello.c

Please see the sample/ directory for details.


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

The main website is http://www.coreboot.org/Libpayload.

For additional information, patches, and discussions, please join the
coreboot mailing list at http://coreboot.org/Mailinglist, where most
libpayload developers are subscribed.


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

See LICENSES.