Contents
How does Linux handle keyboard input?
Keyboard input
- The keyboard sends a scancode to the computer.
- The Linux kernel maps the scancode to a keycode, see Map scancodes to keycodes.
- The keyboard layout maps the keycode to a symbol or keysym, depending on what modifier keys are pressed. For the Linux console, see Linux console/Keyboard configuration.
What is process in Linux kernel?
A kernel process (kproc) exists only in the kernel protection domain and differs from a user process in the ways listed in this section. It is created using the creatp and initp kernel services. It executes only within the kernel protection domain and has all security privileges.
Does kernel create new process?
A kernel process is created by a kernel-mode routine by calling the creatp kernel service. The creatp kernel service allocates and initializes a process block for the process and sets the new process state to idle.
What key is pressed on keyboard Linux?
To check the kernel keycodes, you will need to switch to the console. To switch back to X, you will press and at the same time. To switch to the first Linux console, press , and at the same time. Now run showkey and press the key you want to get info about.
How to capture a key press in Linux?
Real interrupt handler (in keyboard driver) requested as shared interrupt, which allows us also request that interrupt and thus handle it also in our ISR (in addition to ISR in original keyboard driver). Interrupt requesting is done in kbd2_init ().
How does the Linux kernel handle keyboards inputs / outputs?
I’ve got a custom keyboard layout, which is in /usr/share/X11/xkb/symbols/us but it only “works” if X is running. Both virtual terminals and X seems to manage keyboard inputs/outputs in their own way, but presumably they both interface with the (Linux) kernel in some way, which must provide some sort of abstraction for the keyboard hardware.
How to capture a key press and replace it?
If you wonder why we are requesting IRQ with number 1, see at drivers/input/serio/i8042-io.h: Also be sure to check that this IRQ is shared in drivers/input/serio/i8042.c: Here is documentation for i8042 keyboard controller: AT keyboard controller. To avoid magic numbers, you can use next definitions.
How to build KDB into the Linux kernel?
In order to build kdb into the kernel you follow the same steps as you would for kgdb. The main config option for kdb is CONFIG_KGDB_KDB which is called KGDB_KDB: include kdb frontend for kgdb in the config menu.