User:Bellezzasolo/IDT problems: Difference between revisions

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== Problems with IDTs ==
== Problems with IDTs ==
Many of us while OS dev'ing will encounter a problem with IDT's. I won't pretend to be an IDT agony aunt - in fact I've been in trouble myself.
Many of us while OS dev'ing will encounter a problem with IDT's. I won't pretend to be an IDT agony aunt - in fact I've been in trouble myself.
That is why I created this page - a wiki page you can easily access that's in a nice format. Introduction aside, I'll outline the first IDT problem this page has seen.
That is why I created this page - a wiki page you can easily access that's in a nice format. Introduction aside, here are the solved problems.


This is for solved problems. The unsolved ones can be found here on the
This is for solved problems. The unsolved ones can be found here on the
[http://forum.osdev.org/viewtopic.php?f=1&t=24805 Forum]
[http://forum.osdev.org/viewtopic.php?f=1&t=24805 Forum]


== My problem ==
==Problems==
{{stub|nocat=1}}
Please note before you give me GCC specific adivce I have a slightly unusual setup. My setup is MS VC++ 2010 Express SP1 with the [Updated] Windows SDK, enabling 64 bit development. I use a separate assembly layer. I am currently writing my bootloader, but as I will use a custom file system I am currently testing the 32 bit version with the [http://www.brokenthorn.com/Resources/OSDevIndex.html bootloader] available at BrokenThorn, which is a tutorial on a PE kernel. My kernel is higher half at 0xC0000000, and has no memory magager (it relies on the bootloader's). I intend to change this in the near future. It does however, manage it's GDT. My kernel works perfectly without interrupts, and even presents a command line. This is one of the reasons I want IRQ's however, I can only get 1 character. '''This might be changed ''very soon!'''''. When I enable interrupts, the machine reboots. And again.... ad infanatum.
Please post '''''Completed''''' problems here.


First of all check your GDT. Then check padding issues.
Now you understand the environment, this is the bochs output
<pre>
interrupt(): not accessible or not code segment cs = 0x0008
interrupt(): gate descriptor not valid sys seg (vector = 0x0d)

interrupt(): not accessible or not code segment cs = 0x0008
Machine is in protected mode (active)
CS.mode = 32 bit
SS.mode = 32 bit
</pre>
I don't know where I'm going wrong. I am using the ''linear'' address, as told to. If you need the code, here it is:

IDT.h
<source lang="cpp">
//definitions
#define PRESENT 0x80
#define USRPRIV 0x60
#define KRNLPRV 0x0
#define TASK32 0x5
#define INTR16 0x6
#define TRAP16 0x7
#define INTR32 0xE
#define TRAP32 0xF
void setvect(char vect, void(*function)(void), unsigned char priv = (PRESENT|KRNLPRV|INTR32));
void installIDT();
</source>

IDT.cpp
<source lang="cpp">
#include "IDT.h"
#include "..\Asm\Asmlayer.h"
#include <cstddef.h>
#include <stdout.h>
#include "panic.h"
//structures
class IDT_entry {
public:
#ifdef WIN32
unsigned short baseLow;
unsigned short segment;
unsigned char reserved;
unsigned char flags;
unsigned short baseHigh;
#else
unsigned short baseLow;
unsigned short segment;
unsigned char reserved;
unsigned char flags;
unsigned short baseMed;
unsigned int baseHigh;
unsigned int reserved2;
#endif
};
class IDT_reg {
public:
unsigned short limit;
IDT_entry* base;
};

//data
#pragma pack(push,1)
static IDT_reg IDT_register;
#pragma pack(pop)
#pragma pack(push,1)
static IDT_entry IDT [256] = {0};
#pragma pack(pop)

//functions
void setvect(char vect, void(*function)(void), unsigned char priv)
{
#ifdef WIN32
IDT[vect].flags = priv;
IDT[vect].segment = (0x8); //Kernel mode
IDT[vect].reserved = 0;
IDT[vect].baseLow = (unsigned short)(unsigned int)function&0xFFFF;
IDT[vect].baseHigh = (unsigned short)(unsigned int)function>>16;
#else
IDT[vect].flags = priv;
IDT[vect].segment = (0x8); //Kernel mode
IDT[vect].reserved = 0;
IDT[vect].reserved2 = 0;
IDT[vect].baseLow = (unsigned short)(unsigned long long)function&0xFFFF;
IDT[vect].baseMed = (unsigned short)((unsigned long long)function>>16)&0xFFFF;
IDT[vect].baseHigh = (unsigned int)(unsigned long long)function>>16;
#endif
}
void installIDT()
{
if(sizeof(IDT_reg) != 6)
{
Puts("Bad IDT reg\n");
}
#ifdef WIN32
if(sizeof(IDT_entry) != 8)
{
Puts("Bad IDT struct\n");
}
#else
if(sizeof(IDT_entry) != 16)
{
Puts("Bad IDT struct\n");
}
#endif
IDT_register.base = &IDT[0];
#ifdef WIN32
IDT_register.limit = 256*8-1;
#else
IDT_register.limit = 256*16-1;
#endif
lidt(&IDT_register);
}

//ISR's
//These are called from assembly wrappers which handle the brunt
extern "C" {
void defaultHandler()
{
disable();
setColor(0x4,0xF);
Cls();
Puts(panicScreen);
halt();
}

}
</source>

Finally, my assembly routine

<source lang="asm">
BITS 32 ;my 32 bit version
extern @defaultHandler@0
@handlerDefault@0:
pushad
call @defaultHandler@0
popad
iret

BITS 64 ;and my 64 bit version
extern defaultHandler
handlerDefault:
call pusha
call defaultHandler
call popa
iretq
</source>

Thakyou to [[User talk:Alfaomega08|Alfaomega08]] for helping me.

Here is the solution:
<source lang="cpp">
#pragma pack(push, 1)
class IDT_entry
{
// blah blah blah
};
#pragma pack(pop)
</source>
and
<source lang="cpp">
if(sizeof(IDT_reg) != 6)
{
Puts("Bad IDT reg\n");
Halt();
}
</source>

Where Halt is an infinite loop or a "cli; hlt" so that you can actually see the message being put.


== Related links ==
== Related links ==
Line 185: Line 19:
*[[I_Cant_Get_Interrupts_Working|Interrupt problems]]
*[[I_Cant_Get_Interrupts_Working|Interrupt problems]]


[[Category:X86 CPU]]
[[:Category:X86 CPU]]
[[Category:Interrupts]]
[[:Category:Interrupts]]
[[Category:Troubleshooting]]
[[:Category:Troubleshooting]]
[[Category:User drafts]]

Latest revision as of 19:57, 16 June 2024

Problems with IDTs

Many of us while OS dev'ing will encounter a problem with IDT's. I won't pretend to be an IDT agony aunt - in fact I've been in trouble myself. That is why I created this page - a wiki page you can easily access that's in a nice format. Introduction aside, here are the solved problems.

This is for solved problems. The unsolved ones can be found here on the Forum

Problems

This page is a stub.
You can help the wiki by accurately adding more contents to it.

Please post Completed problems here.

First of all check your GDT. Then check padding issues.

Related links

Category:X86 CPU Category:Interrupts Category:Troubleshooting

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