Advance HH, GDT, IDT (details below)

- Implement higher-half in loader with paging (using 4Mb pages)
- Add GDT installation code
- Add IDT installation code (spend a loong time debugging the ISRs!)
- Add CDROM generation scripts
- Add scripts to launch bochs (debug) and qemu (debug)

7 files changed, 114 insertions, 1 deletions

diff --git a/kernel/include/dbglog.h b/kernel/include/dbglog.h
index c8904c6..2f670e8 100644
--- a/kernel/include/dbglog.h
+++ b/kernel/include/dbglog.h
@@ -5,3 +5,5 @@
 void dbglog_setup();
 void dbg_print(const char* str);
 void dbg_printf(const char* format, ...);
+
+/* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/kernel/include/gdt.h b/kernel/include/gdt.h
new file mode 100644
index 0000000..cd66676
--- /dev/null
+++ b/kernel/include/gdt.h
@@ -0,0 +1,64 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+/*	The GDT is one of the x86's descriptor tables. It is used for memory segmentation.
+	Here, we don't use segmentation to separate processes from one another (this is done with paging).
+	We only use segmentation to make the difference between kernel mode (ring 3) and user mode (ring 0) */
+
+/* 	One entry of the table */
+struct gdt_entry {
+	uint16_t limit_low;
+	uint16_t base_low;
+	uint8_t base_middle;
+	uint8_t access;
+	uint8_t granularity;
+	uint8_t base_high;
+} __attribute__((packed));
+typedef struct gdt_entry gdt_entry_t;
+
+/*	Structure defining the whole table : address and size (in bytes). */
+struct gdt_ptr {
+	uint16_t limit;
+	uint32_t base;
+} __attribute__((packed));
+typedef struct gdt_ptr gdt_ptr_t;
+
+/*	The TSS is used for hardware multitasking.
+	We don't use that, but we still need a TSS so that user mode process exceptions
+	can be handled correctly by the kernel.	*/
+struct tss_entry {
+	uint32_t prev_tss;   // The previous TSS - if we used hardware task switching this would form a linked list.
+	uint32_t esp0;       // The stack pointer to load when we change to kernel mode.
+	uint32_t ss0;        // The stack segment to load when we change to kernel mode.
+	uint32_t esp1;       // Unused...
+	uint32_t ss1;
+	uint32_t esp2;
+	uint32_t ss2;
+	uint32_t cr3;
+	uint32_t eip;
+	uint32_t eflags;
+	uint32_t eax;
+	uint32_t ecx;
+	uint32_t edx;
+	uint32_t ebx;
+	uint32_t esp;
+	uint32_t ebp;
+	uint32_t esi;
+	uint32_t edi;
+	uint32_t es;         // The value to load into ES when we change to kernel mode.
+	uint32_t cs;         // The value to load into CS when we change to kernel mode.
+	uint32_t ss;         // The value to load into SS when we change to kernel mode.
+	uint32_t ds;         // The value to load into DS when we change to kernel mode.
+	uint32_t fs;         // The value to load into FS when we change to kernel mode.
+	uint32_t gs;         // The value to load into GS when we change to kernel mode.
+	uint32_t ldt;        // Unused...
+	uint16_t trap;
+	uint16_t iomap_base;
+} __attribute__((packed));
+typedef struct tss_entry tss_entry_t;
+
+void gdt_init();
+
+/* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/kernel/include/idt.h b/kernel/include/idt.h
new file mode 100644
index 0000000..5730f5e
--- /dev/null
+++ b/kernel/include/idt.h
@@ -0,0 +1,40 @@
+#pragma once
+
+/*	The IDT is the system descriptor table that tells the CPU what to do when an interrupt fires.
+	There are three categories of interrupts :
+	- Exceptions ; eg page fault, divide by 0
+	- IRQ : interrupts caused by hardware
+	- System calls : when an applications asks the system to do something */
+
+#include <config.h>
+
+struct idt_entry {
+	uint16_t base_lo;		//Low part of address to jump to
+	uint16_t sel;			//Kernel segment selector
+	uint8_t always0;
+	uint8_t flags;			//Flags
+	uint16_t base_hi;		//High part of address to jump to
+} __attribute__((packed));
+typedef struct idt_entry idt_entry_t;
+
+struct idt_ptr {
+	uint16_t limit;
+	uint32_t base;
+} __attribute__((packed));
+typedef struct idt_ptr idt_ptr_t;
+
+struct registers {
+	uint32_t ds;                  // Data segment selector
+	uint32_t edi, esi, ebp, useless_esp, ebx, edx, ecx, eax; // Pushed by pusha.
+	uint32_t int_no, err_code;    // Interrupt number and error code (if applicable)
+	uint32_t eip, cs, eflags, esp, ss; // Pushed by the processor automatically.
+};
+typedef struct registers registers_t;
+
+typedef void (*isr_handler_t)(registers_t*);
+
+void idt_init();
+//void idt_handleIrq(int number, isr_handler_t func);	//Set IRQ handler
+
+
+/* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/kernel/include/multiboot.h b/kernel/include/multiboot.h
index 8fd9dee..581337a 100644
--- a/kernel/include/multiboot.h
+++ b/kernel/include/multiboot.h
@@ -60,3 +60,4 @@ struct memory_map_t {
 	unsigned long type;
 };
 
+/* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/kernel/include/printf.h b/kernel/include/printf.h
index b37816d..b4e1c1b 100644
--- a/kernel/include/printf.h
+++ b/kernel/include/printf.h
@@ -7,3 +7,4 @@
 int snprintf(char* s, size_t n, const char* format, ...);
 int vsnprintf(char* s, size_t n, const char* format, va_list arg);
 
+/* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/kernel/include/string.h b/kernel/include/string.h
index 3cb0db3..682b25a 100644
--- a/kernel/include/string.h
+++ b/kernel/include/string.h
@@ -13,3 +13,5 @@ char *strchr(const char *str, char c);
 char *strcpy(char *dest, const char *src);
 char *strcat(char *dest, const char *src);
 int strcmp(const char *s1, const char *s2);
+
+/* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/kernel/include/sys.h b/kernel/include/sys.h
index 85cbee6..319cbef 100644
--- a/kernel/include/sys.h
+++ b/kernel/include/sys.h
@@ -7,8 +7,11 @@ void outw(uint16_t port, uint16_t value);
 uint8_t inb(uint16_t port);
 uint16_t inw(uint16_t port);
 
-
 void panic(const char* message, const char* file, int line);
 void panic_assert(const char* assertion, const char* file, int line);
 #define PANIC(s) panic(s, __FILE__, __LINE__);
 #define ASSERT(s) { if (!(s)) panic_assert(#s, __FILE__, __LINE__); }
+
+#define BOCHS_BREAKPOINT asm volatile("xchg %bx, %bx")
+
+/* vim: set ts=4 sw=4 tw=0 noet :*/