a69d682a0b
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>
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libpayload README
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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
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See LICENSES.