OSDev.org

Posted: **Tue Nov 03, 2015 7:19 am**

I have a very big big big trouble.I have spent ten hours to figure it out .But I get nothing

I don't know whether it is a problem with synchronization.

I try to print strings. When call cprintf function ,it do not actually print to screen immediately,instead output to a buffer.

Just @Brendan said.http://forum.osdev.org/viewtopic.php?f=1&t=29754

If without the timer interrupt, the function cprintf works very well.

I want to use timer interrupt to flush buffer.

Once the timer interrupt occurred,the buffer is flushed.

But this process doesn't last long.

It will occur other exceptions,(e.g. debug exception, after several debug exception,will occur illegal opcode exception).

I am very confused.

All those are under the real machine.

I don't know why the timer interrupt always occur with no other code executed under the qeum or boch .

Code: Select all


void os_init_main(multiboot_info_t* m,unsigned int magic)
{
	extern char _bss_start[],_bss_end[];
	if(magic != 0x2BADB002)
		return;
	memset(_bss_start,0,_bss_end - _bss_start);
	mbd = m;
	if(m == NULL)
		return;
	init_console();
	init_mem();
	init_trap();
	init_8259A();
	timerinit();
	disable_8259A_irq(IRQ2_VECTOR);
	enable_8259A_irq(IRQ0_VECTOR);
	cons_flush(tty->p_console);
	unsigned long long i = 0;
	__asm __volatile("sti");
	for(i;;i++){
		int flage = read_eflags();
		__asm __volatile("cli");
		cprintf("%d ",i);	
		write_eflags(flage);
		//cons_flush(tty->p_console);
	}
}

Code: Select all

void foo(int i)
{
	static int j = 0;
	if(i == 32){
		__asm __volatile("movb $0x20,%al\n\toutb %al,$0x20");
		//cprintf("num %d j=%d\n",i,j);
		cons_flush(tty->p_console);	
	}else{
		cprintf("num %d addr:%x j=%d\n",i,rcr2(),j);
		cons_flush(tty->p_console);
		//while(1);
	}
	//cons_flush(tty->p_console);
	j++;
}
void init_trap()
{
	int i ;
	for(i = 0;i < 256; i++) {
		SETGATE(dp[i], 0, 0x10, trap_handlers[i], 0);
	}
	lidt(&idt_pd);
}

Code: Select all

#define TRAPHANDLER_NOEC(name, num)					\
	.globl name;							\
	.type name, @function;						\
	.align 2;							\
	name:								\
	pushl $(num);							\
	call foo;							\
	addl $4,%esp;								\
	jmp _alltraps



.text
.globl _alltraps
_alltraps:
	iret
TRAPHANDLER_NOEC(thdlr0, 0)
TRAPHANDLER_NOEC(thdlr1, 1)
TRAPHANDLER_NOEC(thdlr2, 2)
TRAPHANDLER_NOEC(thdlr3, 3)
.....
TRAPHANDLER_NOEC(thdlr255, 255)

.data
.globl trap_handlers
trap_handlers:
	.long thdlr0
         .......
        .long thdlr255

Code: Select all

void cons_flush(console_t* pcon)
{
	int i;
	static int count = 0;
	static uint32_t buf[1024*1024];

	
	int byte_per_pix = video.bpp/8;
	int Xres = video.Xres;
	int Yres = video.Yres;
	int size = Xres * Yres * byte_per_pix;
	uint32_t *where = buf;

	if (pcon->last_char - pcon->first_char >= video.numchars) {
		pcon->first_char = (pcon->last_char + video.nchars_percolum -(pcon->last_char % video.nchars_percolum)) - video.numchars;	
	} else if (pcon->last_char - pcon->first_char <= 0) {
		
		int i = (pcon->last_char + video.nchars_percolum -(pcon->last_char % video.nchars_percolum));
		pcon->first_char = CONSBUFSIZE - (video.numchars-i);	
	} else {
		//while(1);	
	}
	memset(&pcon->buffer1[pcon->last_char],0x0,4*(video.nchars_percolum -(pcon->last_char % video.nchars_percolum)));
	//video.numchars
	for(i=0;i<video.numchars;i++) {
		char ch = pcon->buffer1[(pcon->first_char+i)%CONSBUFSIZE] & 0xFF;
		int x = (i % video.nchars_percolum) * video.fontw;
		int y = (i / video.nchars_percolum) * video.fonth;
		char r = 0xFF;
		char g = 0xFF;
		char b = 0xFF;
		draw_c(buf,ch,x,y,r,g,b) ;
 	}
	
	for(i=0;i < size / 4;i++) {
		if(pcon->buffer2[i] != buf[i]) {
			pcon->buffer2[i] = buf[i];
			pcon->dispmem_addr[i] = buf[i];	
		}
	}
	
}

Posted: **Tue Nov 03, 2015 12:24 pm**

It will occur other exceptions,(e.g. debug exception, after several debug exception,will occur illegal opcode exception).

Chances are likely your interrupt handlers corrupt your memory.

Posted: **Tue Nov 03, 2015 12:51 pm**

626788149 wrote:

Code: Select all

#define TRAPHANDLER_NOEC(name, num)               \
   .globl name;                     \
   .type name, @function;                  \
   .align 2;                     \
   name:                        \
   pushl $(num);                     \
   call foo;                     \
   addl $4,%esp;                       \
   jmp _alltraps

My guess is the "addl $4, %esp;" line.

If this instruction is meant to throw away the "error number" pushed on to the stack by the CPU, then you need to have another version of this template for interrupts that do not push a value to the stack. (i.e. with this line commented out). You can find the interrupts that push error numbers to the stack here: Exceptions

Also, perhaps on a side note, you are only sending IRQ 0 acknowledgements to the PIC. You probably need to acknowledge IRQ 1-7, and 8-16 to both PICs.

Code: Select all

if(i == 32){
      __asm __volatile("movb $0x20,%al\n\toutb %al,$0x20");
      //cprintf("num %d j=%d\n",i,j);
      cons_flush(tty->p_console);   
   }

Let us know if this helps or not.

Posted: **Tue Nov 03, 2015 8:11 pm**

SpyderTL wrote:
626788149 wrote:
Code: Select all
#define TRAPHANDLER_NOEC(name, num)               \
   .globl name;                     \
   .type name, @function;                  \
   .align 2;                     \
   name:                        \
   pushl $(num);                     \
   call foo;                     \
   addl $4,%esp;                       \
   jmp _alltraps
My guess is the "addl $4, %esp;" line.

If this instruction is meant to throw away the "error number" pushed on to the stack by the CPU, then you need to have another version of this template for interrupts that do not push a value to the stack. (i.e. with this line commented out). You can find the interrupts that push error numbers to the stack here: Exceptions

Because I push a vector number on the stack( pushl $(num) ),so I need pop it out before return back and IRQ0 has no error code.

I find my problem what it is.
If i change codes to this. The problem gone.

Code: Select all

	for(i;;i++){
		__asm __volatile("cli");
		cprintf("%d \n",i);	
		__asm __volatile("sti");
	}

It seem like synchronization problem.
Interrput handler corrupt memory.

Any problem with these code?

Code: Select all

__inline uint32_t
read_eflags(void)
{
	uint32_t eflags;
	__asm __volatile("pushfl; popl %0" : "=r" (eflags));
	return eflags;
}

__inline void
write_eflags(uint32_t eflags)
{
	__asm __volatile("pushl %0; popfl" : : "r" (eflags));
}

Posted: **Tue Nov 03, 2015 8:18 pm**

Combuster wrote:
It will occur other exceptions,(e.g. debug exception, after several debug exception,will occur illegal opcode exception).
Chances are likely your interrupt handlers corrupt your memory.

Yes,just you said.

OSDev.org

A very confusing problem with interrput.

A very confusing problem with interrput.

Re: A very confusing problem with interrput.

Re: A very confusing problem with interrput.

Re: A very confusing problem with interrput.

Re: A very confusing problem with interrput.