Files
system76-coreboot/payloads/libpayload
Patrick Georgi ea0bdf2d54 libpayload: Add zero length packet support to UDC framework
Some IN transfers must be terminated by an empty packet
because otherwise the host wouldn't know.

The zlp() function determines this requirement in
accordance to USB rules: If the transfer's size is aligned
to the maximum packet size, and the host expects a larger
transfer, add the empty packet as a hint.

BRANCH=none
BUG=none
TEST=USB device mode still works

Change-Id: Ia69f3d017f72a3a0e0b21bac72fe97be184c7daa
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: fd0e946e4948a74a9ed15a5eed6ce827b7672a56
Original-Change-Id: I8153cc5bd2ff1c88e383c1dbcddaf1bf72f9194c
Original-Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/250790
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/9784
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-04-18 08:40:28 +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.