Subrata Banik afa39105d8 libpayload: Add x86_64 (64-bit) support
This patch introduces x86_64 (64-bit) support to the payload, building
upon the existing x86 (32-bit) architecture. Files necessary for 64-bit
compilation are now guarded by the `CONFIG_LP_ARCH_X86_64` Kconfig
option.

BUG=b:242829490
TEST=Able to verify all valid combinations between coreboot and
payload with this patch.

Payload Entry Point Behavior with below code.

+----------------+--------------------+----------------------------+
| LP_ARCH_X86_64 | Payload Entry Mode | Description                |
+----------------+--------------------+----------------------------+
| No             | 32-bit             | Direct protected mode init |
+----------------+--------------------+----------------------------+
| Yes            | 32-bit             | Protected to long mode     |
+----------------+--------------------+----------------------------+
| Yes            | 64-bit             | Long mode initialization   |
+----------------+--------------------+----------------------------+

Change-Id: I69fda47bedf1a14807b1515c4aed6e3a1d5b8585
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81968
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2024-05-26 01:26:31 +00:00
..
2021-10-11 12:59:57 +00:00

-------------------------------------------------------------------------------
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 https://www.coreboot.org for details on coreboot.


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

 $ git clone https://review.coreboot.org/coreboot.git

 $ cd coreboot/payloads/libpayload

 $ make menuconfig

 $ make

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

On x86 systems, libpayload will always be 32-bit even if your host OS runs
in 64-bit, so you might have to install the 32-bit libgcc version.
On Debian systems you'd do 'apt-get install gcc-multilib' for example.

Run 'make distclean' before switching boards. This command will remove
your current .config file, so you need 'make menuconfig' again or
'make defconfig' in order to set up configuration. Default configuration
is based on 'configs/defconfig'. See the configs/ directory for examples
of configuration.


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 https://www.coreboot.org/Libpayload.

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


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

See LICENSES.