C Kernel - Runs fine in Qemu but not in VM -


i developing kernel scratch in c. having problem keyboard. in qemu, when press key on keyboard, keypress handled normally. when run in virtualbox or on actual computer, works fine until press key. in virtualbox, when crashes, gives me error code vinf_em_triple_fault. here (important parts) of code:

assembly:

bits 32 section .text         ;multiboot spec         align 4         dd 0x1badb002              ;magic         dd 0x00                    ;flags         dd - (0x1badb002 + 0x00)  global start global keyboard_handler global read_port global write_port global load_idt  extern main         ;this defined in c file extern keyboard_handler_main  read_port:     mov edx, [esp + 4]             ;al lower 8 bits of eax     in al, dx   ;dx lower 16 bits of edx     ret  write_port:     mov   edx, [esp + 4]         mov   al, [esp + 4 + 4]       out   dx, al       ret  load_idt:     mov edx, [esp + 4]     lidt [edx]     sti                 ;turn on interrupts     ret  keyboard_handler:                      call    keyboard_handler_main     iretd  start:     cli                 ;block interrupts     mov esp, stack_space     call main     hlt                 ;halt cpu  section .bss resb 8192; 8kb stack stack_space:

c (the important parts, omitted parts don't involve keyboard):

struct idt_entry{     unsigned short int offset_lowerbits;     unsigned short int selector;     unsigned char zero;     unsigned char type_attr;     unsigned short int offset_higherbits; };  struct idt_entry idt[idt_size]; void idt_init(void) {     unsigned long keyboard_address;     unsigned long idt_address;     unsigned long idt_ptr[2];      /* populate idt entry of keyboard's interrupt */     keyboard_address = (unsigned long)keyboard_handler;     idt[0x21].offset_lowerbits = keyboard_address & 0xffff;     idt[0x21].selector = kernel_code_segment_offset;     idt[0x21].zero = 0;     idt[0x21].type_attr = interrupt_gate;     idt[0x21].offset_higherbits = (keyboard_address & 0xffff0000) >> 16;      /*     ports     *    pic1   pic2     *command 0x20   0xa0     *data    0x21   0xa1     */      /* icw1 - begin initialization */     write_port(0x20 , 0x11);     write_port(0xa0 , 0x11);      /* icw2 - remap offset address of idt */     /*     * in x86 protected mode, have remap pics beyond 0x20 because     * intel have designated first 32 interrupts "reserved" cpu exceptions     */     write_port(0x21 , 0x20);     write_port(0xa1 , 0x28);      /* icw3 - setup cascading */     write_port(0x21 , 0x00);     write_port(0xa1 , 0x00);      /* icw4 - environment info */     write_port(0x21 , 0x01);     write_port(0xa1 , 0x01);     /* initialization finished */      /* mask interrupts */     write_port(0x21 , 0xff);     write_port(0xa1 , 0xff);      /* fill idt descriptor */     idt_address = (unsigned long)idt ;     idt_ptr[0] = (sizeof (struct idt_entry) * idt_size) + ((idt_address & 0xffff) << 16);     idt_ptr[1] = idt_address >> 16 ;      load_idt(idt_ptr); }  void kb_init(void) {     /* 0xfd 11111101 - enables irq1 (keyboard)*/     write_port(0x21 , 0xfd); } void keyboard_handler_main(void) {     unsigned char status;     char keycode;      /* write eoi */     write_port(0x20, 0x20);      status = read_port(keyboard_status_port);     /* lowest bit of status set if buffer not empty */     if (status & 0x01) {         keycode = read_port(keyboard_data_port);         if(keycode < 0){             return;         }             char c = keyboard_map[(unsigned char) keycode]; //keyboard_map converts key codes ascii             (prints char)         }     } } void main(void) {     idt_init();     kb_init();     while(1);     print("welcome code os"); }

and of course compiled linker. why working in qemu not actual computer? (on actual computer works fine until press key.)


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