Files
system76-coreboot/payloads/libpayload
Furquan Shaikh 39292638af libpayload arm64: Initialize and enable MMU
What this change does:
1) Initialize limited page tables as soon as we jump into libpayload. Basically
two ranges are initialized. One is for the BASE_ADDRESS and other is for the
coreboot_tables. With page tables initialized and MMU enabled, we jump into
code to parse coreboot tables.
2) Once coreboot tables are parsed and we have complete picture of the memory,
we perform a complete page table initialzation and enable MMU and then jump to
payload.

Additionally, we also:
1) Initialize DMA memory on our own depending upon the memory map. It ensures
that the DMA buffer is placed in 32-bit memory.

CQ-DEPEND=CL:216826
BUG=chrome-os-partner:31634
BRANCH=None
TEST=Compiles successfully and we are able to start execution of libpayload in
EL2 and reach kernel login prompt

Change-Id: I8a6203e465868bc2a3e5cc377e108f36cc58e2fa
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 7695bb7afe34ea460282125a0be440e8994b01e4
Original-Change-Id: Ie0f47b7759d4ac65a6920f7f2f7502b889afda6d
Original-Signed-off-by: Furquan Shaikh <furquan@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/216824
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Original-Tested-by: Furquan Shaikh <furquan@chromium.org>
Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/8792
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-03-21 13:39:35 +01:00
..
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.