[SOLVED] IDT entries in vm86 are set to wrong positions

[HugeCode]

Hi all. I'm running this simple assembly in vm86:

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xor bh, bh
xor cl, cl
xor ch, ch

mov al, 'A'
mov ah, 0x0A
int 0x10
hier:	jmp hier

When I try to call interrupt, OS halts (VirtualBox) or jumps to 0xffffffff (VMWare). It happens directly on INT instruction:

Screenshot_1.png (1.42 KiB) Viewed 1983 times

00:00:08.329874 eax=00000a41 ebx=0000000e ecx=000003f0 edx=000003fe esi=00100136 edi=0000ff91
00:00:08.329876 eip=00007c0a esp=00ffffc3 ebp=00ffffd3 iopl=0 vm nv dn ei pl zr na po nc
00:00:08.329879 cs={0000 base=0000000000000000 limit=0000ffff flags=000000f3} dr0=00000000 dr1=00000000
00:00:08.329883 ds={0000 base=0000000000000000 limit=0000ffff flags=000000f3} dr2=00000000 dr3=00000000
00:00:08.329886 es={0000 base=0000000000000000 limit=0000ffff flags=000000f3} dr4=00000000 dr5=00000000
00:00:08.329888 fs={1065 base=0000000000010650 limit=0000ffff flags=000000f3} dr6=ffff0ff0 dr7=00000400
00:00:08.329891 gs={fffb base=00000000000fffb0 limit=0000ffff flags=000000f3} cr0=00000011 cr2=00000000
00:00:08.329894 ss={0023 base=0000000000000230 limit=0000ffff flags=000000f3} cr3=00000000 cr4=00000000
00:00:08.329897 gdtr=0000000000008186:0027 idtr=0000000000000000:ffff eflags=00020606

I also tried to trace interrupt addresses, and they seem to be incorrect:

Screenshot_1.png (3.89 KiB) Viewed 1983 times

Does anybody know what can cause such thing? I haven't been manipulating with data on 0x0-0x3FF. Are entries invalid or it's fault of code?
Please help.

Learn to debug.

It's all I can do with VMWare.

[Air]

try to setup stack first:

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xor ax,ax
mov ss,ax
mov sp,0x7c00

[Combuster]

Learn to debug.

It's all I can do with VMWare.

Debugging implies doing your homework, not just dumping everything in the hope someone else fixes it, and especially not code you don't understand and a question that's listed in the FAQ.

RTFM INT.

[rdos]

The IDTR seems to be incorrect. Since you have IOPL=0, all int instructions will trap to protected mode, and since your protected mode IDTR points to zero (the typical real-mode position), I bet you try to execute protection fault by using some real-mode interrupt vectors.

[HugeCode]

OK. I read something in intel manual, but I'm bit confused. Do I have to fill TSS (which I'm not using currently) with some data to have interrupt redirected, or I only need to set VME bit?

When I set VME bit, interrupts are working, but values on 0x0 (and 0x40) are different from that which were there in bootloader. Do I have to save them?

[Combuster]

You need a TSS to be even able to run unprivileged code at all.

[HugeCode]

Ok. Thanks. I'll play with it.