Files
system76-coreboot/payloads/libpayload
Nico Huber 543c79224c libpayload/Makefile.payload: Revise config strategy
Payloads often just use one of the defconfigs for libpayload. When
the `Makefile.payload` was introduced, it also added dependencies
to pass a `make oldconfig` or `make defconfig` for the payload on
to libpayload. Turned out, this creates some dependency madness
when, for instance, `make oldconfig` gets called without a libpay-
load `.config` available, or when we try to include the `.config`
in the `Makefile`.

To make things worse, Kconfig's `Makefile` that is imported from
Linux contains some rarely used paths that are generally incompa-
tible to our environment. So let's get rid of the hard-to-control
automatism.

Payloads that don't want to use a libpayload defconfig need to
clear the `$(LIBPAYLOAD_DEFCONFIG)` variable and manually run
the respective config target to generate a `.config`. To fully
support this, the rule to create a `.config` via `defconfig` is
guarded by `$(LIBPAYLOAD_DEFCONFIG)`. Otherwise we'd have a
spurious, broken recipe when the variable is unset.

We keep the option to call libpayload targets with an `lp-` prefix
for convenience. The existing, explicit targets `lp-defconfig` and
`lp-oldconfig` are replaced with a pattern match, so all config
and other targets should work.

Change-Id: Ie3fcce58d98e248c7182cd47f2a797fe066dd18a
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62273
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Thomas Heijligen <src@posteo.de>
2022-06-15 18:06:05 +00:00
..
2022-06-07 12:34:35 +00:00
2022-03-09 02:18:21 +00:00
2020-03-02 15:03:03 +00:00
2021-10-11 12:59:57 +00:00
2022-06-07 12:34:35 +00:00
2022-06-07 12:34:35 +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.