strange interrupt problem with bochs?

[jinglexy]

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	sti();
	__asm__ __volatile__("ud2a\n\t");
	*(int*)2 = 3;
	CKernel::syshalt();

the "ud2a" can trap into interrupt,
but "*(int*)2 = 3;" can't work?
why it's in bochs?

[bluecode]

Code: Select all

*(int*)2 = 3;

That would only cause a pagefault if the page at virtual address 0 is not mapped or you do not have enough rights to write that page.

[jinglexy]

Code: Select all

*(int*)2 = 3;

That would only cause a pagefault if the page at virtual address 0 is not mapped or you do not have enough rights to write that page.

hi,
i only mapped 3G~4G virtual address, and alloc 32M for bochs,

Code: Select all

void CTrap::test_trap(UNUSED int n)
{
        *(int *)0x2 = 3;			// failed trap in fault
        *(int *)0x40000020 = 3;		// failed trap in fault

        __asm__ __volatile__("ud2a\n\t");	// success trap in fault
}
 

thanks

[jinglexy]

Code: Select all

void CTrap::test_trap(UNUSED int n)
{
        *(int *)0x2 = 3;			// failed trap in fault
        *(int *)0x40000020 = 3;		// success trap in fault

        __asm__ __volatile__("ud2a\n\t");	// success trap in fault
}

i made a little mistake, address 0x40000020 traps in gear,
all runs ok.
thanks

[Combuster]

did you forget to unmap the first 4M ? (tlb flushes and all)

[jinglexy]

did you forget to unmap the first 4M ? (tlb flushes and all)

maybe i forgot, the first 4M memory setup by grub, i just take reference of linux-2.4, and din't see unmap in linux.
kernel only init addresss 3G~3G+memsize , nothing exception