coreboot-kgpe-d16/payloads/libpayload
Nico Huber a69d682a0b libpayload/keyboard: Revise scancode set and translation config
Some background first: The original XT keyboards used what we call
scancode set #1 today. The PC/AT keyboards introduced scancode set #2,
but for compatibility, its controller translated scancodes back to
set #1 by default. Newer keyboards (maybe all we have to deal with)
also support switching the scancode set.

This means the translation option in the controller and the scancode
set selection in the keyboard have to match. In libpayload, we only
support set #1 scancodes. So we either need the controller's trans-
lation on and set #2 selected in the keyboard, or the controller's
translation off and set #1 selected in the keyboard.

Valid configurations:
* SET #1 + XLATE off
* SET #2 + XLATE on

Both with and without the PC_KEYBOARD_AT_TRANSLATED option, we were
only configuring one of the two settings, leaving room for invalid
configurations. With this change, we try to select scancode set #2
first, which seems to be the most supported one, and configure the
controller's translation accordingly. We try to fall back to set #1
on failure.

We also keep translation disabled during configuration steps to
ensure that the controller doesn't accidentally translate confi-
guration data.

On the coreboot side, we leave the controller's translation at its
default setting, unless DRIVERS_PS2_KEYBOARD is enabled. The latter
enables the translation unconditionally. For QEMU this means that
the option effectively toggles the translation, as QEMU's controller
has it disabled by default. This probably made a lot of earlier
testing inconsistent.

Fixes: commit a95a6bf646 (libpayload/drivers/i8402/kbd: Fix qemu)
       The reset introduced there effectively reverted the scancode
       selection made before (because 2 is the default). It's unclear
       if later changes to the code were only necessary to work
       around it.

Change-Id: Iad85af516a7b9f9c0269ff9652ed15ee81700057
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46724
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
2020-12-23 03:29:32 +00:00
..
arch libpayload: Provide API to expose MMU memery ranges for ARM64 2020-12-05 09:45:34 +00:00
bin libpayload: Add compiler.h to compiler parameters 2020-11-08 11:37:04 +00:00
configs Delete mainboard/google/cheza 2020-11-12 01:43:09 +00:00
crypto payloads: Drop unneeded empty lines 2020-09-21 16:20:57 +00:00
curses libpayload/curses: Use <stdbool.h> 2020-10-26 06:57:21 +00:00
drivers libpayload/keyboard: Revise scancode set and translation config 2020-12-23 03:29:32 +00:00
gdb libpayload: gdb: Condition video console init on LP_VIDEO_CONSOLE 2020-06-22 12:24:42 +00:00
include libpayload/i8042: Add API to get/set kbd translation state 2020-12-23 03:29:16 +00:00
libc coreboot tables: Add SPI flash memory map windows to coreboot tables 2020-12-08 22:56:09 +00:00
libcbfs treewide: Remove "this file is part of" lines 2020-05-11 17:11:40 +00:00
liblz4 lz4: Fix out-of-bounds reads 2020-03-02 15:03:03 +00:00
liblzma payloads: Drop unneeded empty lines 2020-09-21 16:20:57 +00:00
libpci libpayload/libpci: Introduce device class attribute in pci_dev 2020-10-17 16:33:55 +00:00
sample treewide: Remove "this file is part of" lines 2020-05-11 17:11:40 +00:00
tests
.gitignore .gitignore: Split into subdirectory files 2020-10-30 07:05:27 +00:00
Doxyfile payloads: Remove/fix trailing whitespace 2018-09-04 12:38:40 +00:00
Kconfig libpayload/keyboard: Revise scancode set and translation config 2020-12-23 03:29:32 +00:00
LICENSES
LICENSE_GPL
Makefile treewide: Remove "this file is part of" lines 2020-05-11 17:11:40 +00:00
Makefile.inc libpayload: Add compiler.h to compiler parameters 2020-11-08 11:37:04 +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.