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Code: Part of Main.c that print key and linker script

    // activate keyboard
    // if keyboard input buffer is full after 0xFFFF counters or does not
    // response with ACK code, activation fails
    if (kActivateKeyboard()) {
    	kPrintString(45, 12, "Pass");
    	// set Num Lock, Caps Lock, Scroll Lock off
    	kChangeKeyboardLED(FALSE, FALSE, FALSE);
    }
    else {
    	kPrintString(45, 12, "Fail");
    	while (1);
    }

    // Simple shell section
    char vcTemp[2] = {0, };
    BYTE bFlags;
    BYTE bTemp;
    int i = 0; 
    while (TRUE) {
        // if key is sent from keyboard
    	if (kIsOutputBufferFull()) {
    		bTemp = kGetKeyboardScanCode();
    		// convert scan code to ASCII code
            if (kConvertScanCodeToASCIICode(bTemp, &(vcTemp[0]), &bFlags)) {
                // print only when key is pressed. In other word,
                // do not print when key is released
            	if (bFlags & KEY_FLAGS_DOWN) {
					kPrintString(i++, 13, vcTemp);
				}
			}
            
    	}
    }
OUTPUT_FORMAT("binary")
OUTPUT_ARCH(i386:x86-64)

SECTIONS {
    /* long mode code resides at 0x200000
     * Instead of concatenating EntryPoint.bin with Kernel.bin, EntryPoint is
     * also involved in the linking process
     */ 

    .text 0x200000 : {
        /* text section of Main file comes first in file*/
        EntryPoint.o(.text)
        Main.o(.text)
        /* text section of other files comes after main in the order of input */
        *(.text)
    }
    . = ALIGN(512);

    /* as .rodata data comes here, operand of instruction that references to a
     * data in .rodata is adjusted
     */
    .rodata : {
        *(.rodata)
    }
    . = ALIGN(512);
    .data : {
        *(.data)
    }
    . = ALIGN(512);
    .bss : {
        *(.bss)
    }

    /* discard all other sections in input files. If this is not specified,
     * ld adds the sections somewhere in the program although instruction to
     * add the sections is not in the script
     */
    /DISCARD/ : {
        *(*)
    }
}

Explanation

Note

  1. Because CPU keep checking PS/2 Controller by looping, it is waste of CPU time. From next chapter, the checking will be processed by interrupt

  2. In the Keyboard.c, there are a lot of duplicate code. The code will be refactored later

  3. If you compile and run kernel without modifying linker script, kernel reboot when you hit a key. This is because linker script discarded .bss and .data sections when linking. This means that some code references wrong address and some data is inserted into image file. To solve the problem, It is required to involve .bss and .data section into program.

MINT64OS Characteristics

  1. Memory Layout up to CH11

    • start(inclusive) ~ end(exclusive)
    • 0x00000 ~ 0x00400 (Interrupt Vector Table)
    • 0x07C00 ~ 0x07E00 (Bootloader)
    • 0x07E00 ~ 0x10000 (Stack for real mode and protected mode)
    • 0x10000 ~ 0x10400 (32 bit code of OS; EntryPoint.S + Main.c + ...)
    • 0xA0000 ~ ... (video memory for graphic mode)
    • 0xB8000 ~ ... (video memory for text mode)
    • 0x100000(1MB) ~ 0x142000(1MB+264KB) (IA-32 mode page table tree structure)
    • 0x200000(2MB) ~ ... (64 bit code of OS; EntryPoint.S + Main.c + ...)
    • 0x600000(6MB) ~ 0x6FFFFF(7MB) (Stack for long mode)