├── LICENSE ├── README.md ├── binary_x86 └── kernel ├── kernel.asm ├── kernel.c ├── keyboard_map.h └── link.ld /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 2, June 1991 3 | 4 | Copyright (C) 1989, 1991 Free Software Foundation, Inc., 5 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 6 | Everyone is permitted to copy and distribute verbatim copies 7 | of this license document, but changing it is not allowed. 8 | 9 | Preamble 10 | 11 | The licenses for most software are designed to take away your 12 | freedom to share and change it. By contrast, the GNU General Public 13 | License is intended to guarantee your freedom to share and change free 14 | software--to make sure the software is free for all its users. This 15 | General Public License applies to most of the Free Software 16 | Foundation's software and to any other program whose authors commit to 17 | using it. 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It is safest 289 | to attach them to the start of each source file to most effectively 290 | convey the exclusion of warranty; and each file should have at least 291 | the "copyright" line and a pointer to where the full notice is found. 292 | 293 | {description} 294 | Copyright (C) {year} {fullname} 295 | 296 | This program is free software; you can redistribute it and/or modify 297 | it under the terms of the GNU General Public License as published by 298 | the Free Software Foundation; either version 2 of the License, or 299 | (at your option) any later version. 300 | 301 | This program is distributed in the hope that it will be useful, 302 | but WITHOUT ANY WARRANTY; without even the implied warranty of 303 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 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Of course, the commands you use may 322 | be called something other than `show w' and `show c'; they could even be 323 | mouse-clicks or menu items--whatever suits your program. 324 | 325 | You should also get your employer (if you work as a programmer) or your 326 | school, if any, to sign a "copyright disclaimer" for the program, if 327 | necessary. Here is a sample; alter the names: 328 | 329 | Yoyodyne, Inc., hereby disclaims all copyright interest in the program 330 | `Gnomovision' (which makes passes at compilers) written by James Hacker. 331 | 332 | {signature of Ty Coon}, 1 April 1989 333 | Ty Coon, President of Vice 334 | 335 | This General Public License does not permit incorporating your program into 336 | proprietary programs. If your program is a subroutine library, you may 337 | consider it more useful to permit linking proprietary applications with the 338 | library. If this is what you want to do, use the GNU Lesser General 339 | Public License instead of this License. -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | mkeykernel 2 | ======= 3 | 4 | This is a kernel that can read the characters `a-z` and `0-9` from the keyboard and print them on screen. 5 | 6 | See the repo [mkernel](http://github.com/arjun024/mkernel) which is a minimal kernel that prints a string on the screen. mkeykernel just extends this to include keyboard support. 7 | 8 | 9 | #### Blog post #### 10 | 11 | [Kernel 201 - Let’s write a Kernel with keyboard and screen support](http://arjunsreedharan.org/post/99370248137/kernel-201-lets-write-a-kernel-with-keyboard-and) 12 | 13 | #### Build commands #### 14 | ``` 15 | nasm -f elf32 kernel.asm -o kasm.o 16 | ``` 17 | ``` 18 | gcc -m32 -c kernel.c -o kc.o 19 | ``` 20 | ``` 21 | ld -m elf_i386 -T link.ld -o kernel kasm.o kc.o 22 | ``` 23 | 24 | If you get the following error message: 25 | ``` 26 | kc.o: In function `idt_init': 27 | kernel.c:(.text+0x129): undefined reference to `__stack_chk_fail' 28 | ``` 29 | 30 | compile with the `-fno-stack-protector` option: 31 | ``` 32 | gcc -fno-stack-protector -m32 -c kernel.c -o bin/kc.o 33 | ``` 34 | 35 | #### Test on emulator #### 36 | ``` 37 | qemu-system-i386 -kernel kernel 38 | ``` 39 | 40 | #### Get to boot #### 41 | GRUB requires your kernel executable to be of the pattern `kernel-`. 42 | 43 | So, rename the kernel: 44 | 45 | ``` 46 | mv kernel kernel-701 47 | ``` 48 | 49 | Copy it to your boot partition (assuming you are superuser): 50 | 51 | ``` 52 | cp kernel-701 /boot/kernel-701 53 | ``` 54 | 55 | Configure your grub/grub2 similar to what is given in `_grub_grub2_config` folder of [mkernel repo](http://github.com/arjun024/mkernel). 56 | 57 | Reboot. 58 | 59 | Voila! 60 | 61 | ![kernel screenshot](http://31.media.tumblr.com/1afd75b433b13df613fa0c2301977893/tumblr_inline_ncy1p0kSGj1rivrqc.png "Screenshot") 62 | -------------------------------------------------------------------------------- /binary_x86/kernel: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/arjun024/mkeykernel/0a9f24bd2521f73df0d00728d0a47ec6bb439f0a/binary_x86/kernel -------------------------------------------------------------------------------- /kernel.asm: -------------------------------------------------------------------------------- 1 | ; Copyright (C) 2014 Arjun Sreedharan 2 | ; License: GPL version 2 or higher http://www.gnu.org/licenses/gpl.html 3 | 4 | bits 32 5 | section .text 6 | ;multiboot spec 7 | align 4 8 | dd 0x1BADB002 ;magic 9 | dd 0x00 ;flags 10 | dd - (0x1BADB002 + 0x00) ;checksum. m+f+c should be zero 11 | 12 | global start 13 | global keyboard_handler 14 | global read_port 15 | global write_port 16 | global load_idt 17 | 18 | extern kmain ;this is defined in the c file 19 | extern keyboard_handler_main 20 | 21 | read_port: 22 | mov edx, [esp + 4] 23 | ;al is the lower 8 bits of eax 24 | in al, dx ;dx is the lower 16 bits of edx 25 | ret 26 | 27 | write_port: 28 | mov edx, [esp + 4] 29 | mov al, [esp + 4 + 4] 30 | out dx, al 31 | ret 32 | 33 | load_idt: 34 | mov edx, [esp + 4] 35 | lidt [edx] 36 | sti ;turn on interrupts 37 | ret 38 | 39 | keyboard_handler: 40 | call keyboard_handler_main 41 | iretd 42 | 43 | start: 44 | cli ;block interrupts 45 | mov esp, stack_space 46 | call kmain 47 | hlt ;halt the CPU 48 | 49 | section .bss 50 | resb 8192; 8KB for stack 51 | stack_space: 52 | -------------------------------------------------------------------------------- /kernel.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright (C) 2014 Arjun Sreedharan 3 | * License: GPL version 2 or higher http://www.gnu.org/licenses/gpl.html 4 | */ 5 | #include "keyboard_map.h" 6 | 7 | /* there are 25 lines each of 80 columns; each element takes 2 bytes */ 8 | #define LINES 25 9 | #define COLUMNS_IN_LINE 80 10 | #define BYTES_FOR_EACH_ELEMENT 2 11 | #define SCREENSIZE BYTES_FOR_EACH_ELEMENT * COLUMNS_IN_LINE * LINES 12 | 13 | #define KEYBOARD_DATA_PORT 0x60 14 | #define KEYBOARD_STATUS_PORT 0x64 15 | #define IDT_SIZE 256 16 | #define INTERRUPT_GATE 0x8e 17 | #define KERNEL_CODE_SEGMENT_OFFSET 0x08 18 | 19 | #define ENTER_KEY_CODE 0x1C 20 | 21 | extern unsigned char keyboard_map[128]; 22 | extern void keyboard_handler(void); 23 | extern char read_port(unsigned short port); 24 | extern void write_port(unsigned short port, unsigned char data); 25 | extern void load_idt(unsigned long *idt_ptr); 26 | 27 | /* current cursor location */ 28 | unsigned int current_loc = 0; 29 | /* video memory begins at address 0xb8000 */ 30 | char *vidptr = (char*)0xb8000; 31 | 32 | struct IDT_entry { 33 | unsigned short int offset_lowerbits; 34 | unsigned short int selector; 35 | unsigned char zero; 36 | unsigned char type_attr; 37 | unsigned short int offset_higherbits; 38 | }; 39 | 40 | struct IDT_entry IDT[IDT_SIZE]; 41 | 42 | 43 | void idt_init(void) 44 | { 45 | unsigned long keyboard_address; 46 | unsigned long idt_address; 47 | unsigned long idt_ptr[2]; 48 | 49 | /* populate IDT entry of keyboard's interrupt */ 50 | keyboard_address = (unsigned long)keyboard_handler; 51 | IDT[0x21].offset_lowerbits = keyboard_address & 0xffff; 52 | IDT[0x21].selector = KERNEL_CODE_SEGMENT_OFFSET; 53 | IDT[0x21].zero = 0; 54 | IDT[0x21].type_attr = INTERRUPT_GATE; 55 | IDT[0x21].offset_higherbits = (keyboard_address & 0xffff0000) >> 16; 56 | 57 | /* Ports 58 | * PIC1 PIC2 59 | *Command 0x20 0xA0 60 | *Data 0x21 0xA1 61 | */ 62 | 63 | /* ICW1 - begin initialization */ 64 | write_port(0x20 , 0x11); 65 | write_port(0xA0 , 0x11); 66 | 67 | /* ICW2 - remap offset address of IDT */ 68 | /* 69 | * In x86 protected mode, we have to remap the PICs beyond 0x20 because 70 | * Intel have designated the first 32 interrupts as "reserved" for cpu exceptions 71 | */ 72 | write_port(0x21 , 0x20); 73 | write_port(0xA1 , 0x28); 74 | 75 | /* ICW3 - setup cascading */ 76 | write_port(0x21 , 0x00); 77 | write_port(0xA1 , 0x00); 78 | 79 | /* ICW4 - environment info */ 80 | write_port(0x21 , 0x01); 81 | write_port(0xA1 , 0x01); 82 | /* Initialization finished */ 83 | 84 | /* mask interrupts */ 85 | write_port(0x21 , 0xff); 86 | write_port(0xA1 , 0xff); 87 | 88 | /* fill the IDT descriptor */ 89 | idt_address = (unsigned long)IDT ; 90 | idt_ptr[0] = (sizeof (struct IDT_entry) * IDT_SIZE) + ((idt_address & 0xffff) << 16); 91 | idt_ptr[1] = idt_address >> 16 ; 92 | 93 | load_idt(idt_ptr); 94 | } 95 | 96 | void kb_init(void) 97 | { 98 | /* 0xFD is 11111101 - enables only IRQ1 (keyboard)*/ 99 | write_port(0x21 , 0xFD); 100 | } 101 | 102 | void kprint(const char *str) 103 | { 104 | unsigned int i = 0; 105 | while (str[i] != '\0') { 106 | vidptr[current_loc++] = str[i++]; 107 | vidptr[current_loc++] = 0x07; 108 | } 109 | } 110 | 111 | void kprint_newline(void) 112 | { 113 | unsigned int line_size = BYTES_FOR_EACH_ELEMENT * COLUMNS_IN_LINE; 114 | current_loc = current_loc + (line_size - current_loc % (line_size)); 115 | } 116 | 117 | void clear_screen(void) 118 | { 119 | unsigned int i = 0; 120 | while (i < SCREENSIZE) { 121 | vidptr[i++] = ' '; 122 | vidptr[i++] = 0x07; 123 | } 124 | } 125 | 126 | void keyboard_handler_main(void) 127 | { 128 | unsigned char status; 129 | char keycode; 130 | 131 | /* write EOI */ 132 | write_port(0x20, 0x20); 133 | 134 | status = read_port(KEYBOARD_STATUS_PORT); 135 | /* Lowest bit of status will be set if buffer is not empty */ 136 | if (status & 0x01) { 137 | keycode = read_port(KEYBOARD_DATA_PORT); 138 | if(keycode < 0) 139 | return; 140 | 141 | if(keycode == ENTER_KEY_CODE) { 142 | kprint_newline(); 143 | return; 144 | } 145 | 146 | vidptr[current_loc++] = keyboard_map[(unsigned char) keycode]; 147 | vidptr[current_loc++] = 0x07; 148 | } 149 | } 150 | 151 | void kmain(void) 152 | { 153 | const char *str = "my first kernel with keyboard support"; 154 | clear_screen(); 155 | kprint(str); 156 | kprint_newline(); 157 | kprint_newline(); 158 | 159 | idt_init(); 160 | kb_init(); 161 | 162 | while(1); 163 | } 164 | -------------------------------------------------------------------------------- /keyboard_map.h: -------------------------------------------------------------------------------- 1 | /* The following array is taken from 2 | http://www.osdever.net/bkerndev/Docs/keyboard.htm 3 | All credits where due 4 | */ 5 | 6 | unsigned char keyboard_map[128] = 7 | { 8 | 0, 27, '1', '2', '3', '4', '5', '6', '7', '8', /* 9 */ 9 | '9', '0', '-', '=', '\b', /* Backspace */ 10 | '\t', /* Tab */ 11 | 'q', 'w', 'e', 'r', /* 19 */ 12 | 't', 'y', 'u', 'i', 'o', 'p', '[', ']', '\n', /* Enter key */ 13 | 0, /* 29 - Control */ 14 | 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', ';', /* 39 */ 15 | '\'', '`', 0, /* Left shift */ 16 | '\\', 'z', 'x', 'c', 'v', 'b', 'n', /* 49 */ 17 | 'm', ',', '.', '/', 0, /* Right shift */ 18 | '*', 19 | 0, /* Alt */ 20 | ' ', /* Space bar */ 21 | 0, /* Caps lock */ 22 | 0, /* 59 - F1 key ... > */ 23 | 0, 0, 0, 0, 0, 0, 0, 0, 24 | 0, /* < ... F10 */ 25 | 0, /* 69 - Num lock*/ 26 | 0, /* Scroll Lock */ 27 | 0, /* Home key */ 28 | 0, /* Up Arrow */ 29 | 0, /* Page Up */ 30 | '-', 31 | 0, /* Left Arrow */ 32 | 0, 33 | 0, /* Right Arrow */ 34 | '+', 35 | 0, /* 79 - End key*/ 36 | 0, /* Down Arrow */ 37 | 0, /* Page Down */ 38 | 0, /* Insert Key */ 39 | 0, /* Delete Key */ 40 | 0, 0, 0, 41 | 0, /* F11 Key */ 42 | 0, /* F12 Key */ 43 | 0, /* All other keys are undefined */ 44 | }; -------------------------------------------------------------------------------- /link.ld: -------------------------------------------------------------------------------- 1 | OUTPUT_FORMAT(elf32-i386) 2 | ENTRY(start) 3 | SECTIONS 4 | { 5 | . = 0x100000; 6 | .text : { *(.text) } 7 | .data : { *(.data) } 8 | .bss : { *(.bss) } 9 | } 10 | --------------------------------------------------------------------------------