coreboot-kgpe-d16/payloads/libpayload
Julius Werner 2296479dfd libpayload: cbfs: Add cbfs_handle API for more fine-grained accesses
The libpayload CBFS APIs are pretty old and clunky, primarily because of
the way the cbfs_media struct may or may not be passed in and may be
initialized inside the API calls in a way that cannot be passed back out
again. Due to this, the only real CBFS access function we have always
reads a whole file with all metadata, and everything else has to build
on top of that. This makes certain tasks like reading just a file
attribute very inefficient on non-memory-mapped platforms (because you
always have to map the whole file).

This patch isn't going to fix the world, but will allow a bit more
flexibility by bolting a new API on top which uses a struct cbfs_handle
to represent a found but not yet read file. A cbfs_handle contains a
copy of the cbfs_media needed to read the file, so it can be kept and
passed around to read individual parts of it after the initial lookup.
The existing (non-media) legacy API is retained for backwards
compatibility, as is cbfs_file_get_contents() (which is most likely what
more recent payloads would have used, and also a good convenience
wrapper for the most simple use case), but they are now implemented on
top of the new API.

TEST=Booted Oak, made sure that firmware screens and software sync
worked okay.

Change-Id: I269f3979e77ae691ee9d4e1ab564eff6d45b7cbe
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/14810
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
2016-05-17 22:48:28 +02:00
..
arch libpayload/arm64: Mark existing framebuffer as DMAable 2016-05-09 08:30:56 +02:00
bin libpayload: Move base address, stack and heap size to Kconfig 2016-03-15 20:53:38 +01:00
configs libpayload: Add nyan config 2016-05-09 07:49:57 +02:00
crypto libpayload: Make Kconfig bools use IS_ENABLED() 2015-06-30 18:55:15 +02:00
curses libpayload: PDCurses: Remove trailing whitespace 2015-11-20 16:27:36 +01:00
drivers libpayload: ipq40xx: Introduce timer and uart driver 2016-05-09 08:53:24 +02:00
gdb tree: drop last paragraph of GPL copyright header 2015-10-31 21:37:39 +01:00
include libpayload: cbfs: Add cbfs_handle API for more fine-grained accesses 2016-05-17 22:48:28 +02:00
libc libpayload/libc: Fix memset/sizeof usage 2016-04-06 13:33:07 +02:00
libcbfs libpayload: cbfs: Add cbfs_handle API for more fine-grained accesses 2016-05-17 22:48:28 +02:00
liblz4 cbfs: Add LZ4 in-place decompression support for pre-RAM stages 2016-02-22 21:38:37 +01:00
liblzma lzma: Return correct amount of decompressed bytes 2015-07-06 09:40:37 +02:00
libpci
sample
tests
Doxyfile
Kconfig libpayload: ipq40xx: Introduce timer and uart driver 2016-05-09 08:53:24 +02:00
LICENSES libpayload: Add LZ4 decompression algorithm 2015-07-09 00:10:16 +02:00
LICENSE_GPL
Makefile libpayload: update junit.xml target, clean up output 2016-03-25 18:18:27 +01:00
Makefile.inc libpayload: update junit.xml target, clean up output 2016-03-25 18:18:27 +01:00
README

README

-------------------------------------------------------------------------------
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.