coreboot-kgpe-d16/payloads/libpayload
Julius Werner 6af43804c5 libpayload: usb: Try to avoid reusing device addresses
We recently changed the USB stack to detach devices aggressively that we
don't intend to use. This alone is not really a problem, but it
exarcerbates the fact that our device detachment itself is not very
good. We destroy any local info about the device, but we don't properly
disable the offending port. The device keeps thinking that it's active,
and if we later try to reuse that device address for another device
things become confused.

The real fix would be to properly disable all ports that we don't intend
to use. Unfortunately, this isn't really possible in our current
device/hub polymorphism structure, and I don't want to hack a new
disable_port() callback into usbdev_t that really doesn't belong there.
We will only be able to fix this cleanly after we ported all root hubs
to the generic_hub interface.

Until then, an easy workaround is to just avoid reusing addresses as
long as possible. This is firmware, so the chance that we'll ever run
through 127 devices is really small in practice. Even if we ever fix the
underlying issue, it's probably a smart precaution to keep.

BRANCH=nyan,rambi
BUG=chrome-os-partner:28328
TEST=Boot from a hub that has an "unknown" device in an earlier port
than the stick you want to boot from, make sure you can still boot.

Original-Change-Id: I9b522dd8cbcd441e8c3b8781fcecd2effa0f23ee
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/197420
Original-Reviewed-by: Shawn Nematbakhsh <shawnn@chromium.org>
Original-Reviewed-by: David Hendricks <dhendrix@chromium.org>
(cherry picked from commit 28b48aa69b55a983226edf2ea616f33cd4b959e2)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: Id4c5c92e75d6b5a7e8f0ee3e396c69c4efd13176
Reviewed-on: http://review.coreboot.org/7881
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
2014-12-22 21:44:43 +01:00
..
arch arm: Fix minor mistake in cache maintenance assembly 2014-12-15 23:27:41 +01:00
bin ARM: Generalize armv7 as arm. 2014-09-08 18:59:23 +02:00
configs libpayload: Remove config.panther 2014-11-13 06:22:25 +01:00
crypto libpayload: Change CONFIG_* to CONFIG_LP_* in the kconfig. 2014-08-05 18:44:08 +02:00
curses libpayload: Change CONFIG_* to CONFIG_LP_* in the kconfig. 2014-08-05 18:44:08 +02:00
drivers libpayload: usb: Try to avoid reusing device addresses 2014-12-22 21:44:43 +01:00
include libpayload: usb: Try to avoid reusing device addresses 2014-12-22 21:44:43 +01:00
libc libpayload: console: Allow output drivers to print whole strings at once 2014-12-22 21:44:37 +01:00
libcbfs cbfs: Fix overwalk on file scan 2014-08-10 22:25:07 +02:00
liblzma LZMA: Add a version of ulzma which takes the input and output buffer sizes. 2014-08-10 22:29:51 +02:00
libpci libpayload: minor cleanups 2012-04-04 00:40:31 +02:00
sample libpayload: Fix missed CONFIG_ -> CONFIG_LP_ substitutions 2014-10-17 11:24:15 +02:00
tests libpayload: Change CONFIG_X86_SERIAL_CONSOLE to CONFIG_8250_SERIAL_CONSOLE 2014-08-28 01:40:48 +02:00
util libpayload: also support armv7-a toolchain 2014-10-16 15:54:16 +02:00
Config.in libpayload: Add minimal support for PL011 UART 2014-11-13 06:23:17 +01:00
Doxyfile Run doxygen -u on doxygen configuration files 2010-06-28 10:40:38 +00:00
LICENSES
Makefile libpayload: Don't use default path for kconfig 2014-10-17 11:25:10 +02:00
Makefile.inc libpayload: Build libpayload with debugging info turned up all the way. 2014-09-29 19:29:30 +02:00
README libpayload, superiotool: README: Prepend `coreboot/` to path of change directory line 2013-04-04 17:22:15 +02:00

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.