coreboot-kgpe-d16/payloads/libpayload
Nico Huber e79595def5 libpayload: Use interrupt transfers for USB hubs
In interactive payloads, the USB stack's poll procedure is implicitly
called from the UI loop. Since all USB control transfers are handled
synchronously, polling hubs with these slows the UI significantly down.

So switch to interrupt transfers that are done asynchronously and only
perform control transfers when the hub reported a status change.

We use the interrupt endpoint's max packet size instead of the theo-
retical transfer length of `(bNrPorts + 1) / 8` as Linux' code mentions
hubs that return too much data.

Change-Id: I5af02d63e4b8e1451b160b77f3611b93658a7a48
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/18499
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
2019-09-18 12:58:50 +00:00
..
arch libpayload: Align main() data types 2019-04-05 22:37:19 +00:00
bin
configs payloads/libpayload: Update a Makefile for sample libpayload 2019-06-21 09:16:36 +00:00
crypto payloads: Replace all IS_ENABLED(CONFIG_XXX) with CONFIG(XXX) 2019-03-07 17:15:30 +00:00
curses libpayload: Enable -Wimplicit-fallthrough 2019-07-21 17:17:42 +00:00
drivers libpayload: Use interrupt transfers for USB hubs 2019-09-18 12:58:50 +00:00
gdb
include libpayload/usb: add USB 3.1 GEN2 support 2019-08-27 07:21:00 +00:00
libc Add buffer_to/from_fifo32(_prefix) helpers 2019-08-22 10:36:22 +00:00
libcbfs payloads: Replace all IS_ENABLED(CONFIG_XXX) with CONFIG(XXX) 2019-03-07 17:15:30 +00:00
liblz4
liblzma
libpci
sample payloads/libpayload: Update a Makefile for sample libpayload 2019-06-21 09:16:36 +00:00
tests
Doxyfile
Kconfig libpayload: Add UART for qcs405 2019-06-04 14:14:58 +00:00
LICENSES
LICENSE_GPL
Makefile
Makefile.inc Makefile.inc, payloads: Enable -Wvla 2019-08-20 20:57:01 +00:00
README payloads/libpayload: Update a Makefile for sample libpayload 2019-06-21 09:16:36 +00:00

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 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.