Nucleus

diff --git a/kernel/acpi/apic.c b/kernel/acpi/apic.c
index 6051636..7f9935c 100644
--- a/kernel/acpi/apic.c
+++ b/kernel/acpi/apic.c
@@ -58,6 +58,7 @@ int apic = 0;
 size_t ncpus = 1;
 uintptr_t lapicPtr, ioapicPtr;
 cpu_t lapicIds[MAX_CPUS], lapicNums[MAX_CPUS];
+extern uintptr_t stacks[];
 
 /* Enable APIC */
 static void
@@ -176,10 +177,11 @@ init_apic(struct SDTHeader *header)
 	uint32_t i, j;
 	uintptr_t apTrampoline = 0x1000, stack;
 	memcpy((void *) apTrampoline, &ap_trampoline, PAGE_SIZE);
+	*((uint32_t *) (apTrampoline + 0xFFC)) = (uintptr_t) stacks;
 	for (i = 1; i < ncpus; i++) {
 		/* Give each processor a separate stack */
-		stack = alloc_frame() + PAGE_SIZE - sizeof(uintptr_t);
-		*((uint32_t *) (apTrampoline + 0xF00 + i)) = stack;
+		stacks[i] = alloc_frame() + PAGE_SIZE;
+//		*((uint32_t *) (apTrampoline + 0xC00) + i) = stacks[i];
 		/* Send INIT IPI */
 		LAPIC(0x280) = 0;
 		LAPIC(0x310) = (LAPIC(0x310) & 0x00FFFFFF)
@@ -239,5 +241,5 @@ send_ipi(cpu_t target, uint8_t num)
 	             | (lapicIds[target] << 24);
 	LAPIC(0x300) = (LAPIC(0x300) & 0xFFF32000)
 	             | (0x5000 + num + 48);
-	while ((LAPIC(0x300) >> 12) & 1);
+	do asm("pause":::"memory"); while (LAPIC(0x300) & (1 << 12));
 }
diff --git a/kernel/acpi/trampoline.S b/kernel/acpi/trampoline.S
index 3230e85..c807524 100644
--- a/kernel/acpi/trampoline.S
+++ b/kernel/acpi/trampoline.S
@@ -48,9 +48,8 @@ ap_pm:
 	incl %eax
 	movl %eax, apId
 
-	movl $0x1F00, %esi
-	movl (%esi,%eax), %ebx
-	movl %ebx, %esp
+	movl 0x1FFC, %esi
+	movl (%esi,%eax,4), %esp
 	movl %esp, %ebp
 
 	sti
diff --git a/kernel/cpu.c b/kernel/cpu.c
index e7ab334..ba59986 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -34,6 +34,7 @@ void send_ipi(cpu_t target, uint8_t num);
 
 Processor __seg_gs *const cpu = 0;
 Processor *cpus[MAX_CPUS];
+uintptr_t stacks[MAX_CPUS];
 
 /* Per-CPU setup */
 void
diff --git a/kernel/gdt.c b/kernel/gdt.c
index 7e8a1a4..fbdfb82 100644
--- a/kernel/gdt.c
+++ b/kernel/gdt.c
@@ -33,7 +33,7 @@ static struct GDTEntry {
 	uint8_t baseMiddle, access, gran, baseHigher;
 } __attribute__((packed)) *gdt[MAX_CPUS]; /* Per CPU */
 
-#define GDT_OFFSET(i) (i * sizeof(struct GDTEntry))
+#define GDT_OFFSET(i) ((i) * sizeof(struct GDTEntry))
 
 /* Structure for a TSS Entry */
 static struct TSSEntry {
@@ -83,6 +83,7 @@ cpu_load_gdt(void)
 
 	memset(gdt[CPUID], 0, size);
 
+	/* Create gate entries */
 	gdt_set_gate(GDT_NULL,      0x00000000, 0x00000000, 0x00, 0x00);
 	gdt_set_gate(GDT_KERN_CODE, 0x00000000, 0xFFFFFFFF, 0x9A, 0xCF);
 	gdt_set_gate(GDT_KERN_DATA, 0x00000000, 0xFFFFFFFF, 0x92, 0xCF);
@@ -91,20 +92,22 @@ cpu_load_gdt(void)
 	gdt_set_gate(GDT_FS,        0x00000000, 0xFFFFFFFF, 0xF2, 0xCF);
 	gdt_set_gate(GDT_GS,        0x00000000, 0xFFFFFFFF, 0xF2, 0xCF);
 
+	/* Create TSS entry */
 	uint32_t addr = (uint32_t) (gdt[CPUID] + (GDT_TSS + 1));
 	gdt_set_gate(GDT_TSS, addr, sizeof(struct TSSEntry) - 1, 0xE9, 0);
 
+	/* TSS */
 	tss[CPUID] = (void *) addr;
 	tss[CPUID]->ss0 = 0x10;
-	tss[CPUID]->esp0 = 0xF0800000 - sizeof(uintptr_t);
 	tss[CPUID]->cs = GDT_OFFSET(GDT_KERN_CODE) | 0;
 	tss[CPUID]->ds = GDT_OFFSET(GDT_KERN_DATA) | 0;
 	tss[CPUID]->es = tss[CPUID]->ss = tss[CPUID]->ds;
 	tss[CPUID]->fs = tss[CPUID]->gs = GDT_OFFSET(GDT_FS) | 3;
 	tss[CPUID]->iomapBase = sizeof(struct TSSEntry);
 
+	/* Load table */
 	struct DescRecord ptr = {
-		.limit = sizeof(struct GDTEntry) * (GDT_TSS + 1),
+		.limit = GDT_OFFSET(GDT_TSS + 1),
 		.base = (uintptr_t) gdt[CPUID],
 	};
 	asm volatile("lgdt %0" :: "m" (ptr));
@@ -132,3 +135,11 @@ set_gs_base(uintptr_t base)
 	gs->baseHigher = (base >> 24) & 0xFF;
 	asm volatile("mov %0, %%gs" :: "r" (GDT_OFFSET(GDT_GS) | 3));
 }
+
+/* Set the used kernel stack */
+void
+set_kernel_stack(uintptr_t top)
+{
+	ASSERT((top & 0xF) == 0);
+	tss[cpu->id]->esp0 = top;
+}
diff --git a/kernel/idt.c b/kernel/idt.c
index 0f2bdfd..6e04543 100644
--- a/kernel/idt.c
+++ b/kernel/idt.c
@@ -31,10 +31,13 @@ install_idt_entry(uint8_t num, void *addr)
 	if (num < 32)
 		type = 0x8F; /* Trap gate for exceptions */
 
+	if (num == 0x80)
+		type |= 3 << 5; /* Allowed from ring 3 */
+
 	IDT[num].offsetLower = (uintptr_t) addr & 0xFFFF;
 	IDT[num].selector = 0x08;
 	IDT[num].zero = 0;
-	IDT[num].typeAttr = type | 0x60; /* Allowed from ring 3 */
+	IDT[num].typeAttr = type;
 	IDT[num].offsetHigher = (uintptr_t) addr >> 16;
 }
 
@@ -58,8 +61,13 @@ isr_handler(struct InterruptFrame frame)
 
 	/* Run registered handler */
 	int_handler_t handler = interrupts[frame.intnum];
-	if (handler)
+	struct InterruptFrame *oldFrame;
+	if (handler) {
+		oldFrame = cpu->frame;
+		cpu->frame = &frame;
 		handler(&frame);
+		cpu->frame = oldFrame;
+	}
 }
 
 /* Register an exception handler */
diff --git a/kernel/start.S b/kernel/start.S
index 96048e2..fe842e8 100644
--- a/kernel/start.S
+++ b/kernel/start.S
@@ -9,9 +9,10 @@ header:
 	.long 0, 1280, 1024, 32
 
 .section .bss, "aw", @nobits
+.global stackBottom
 .global stackTop
 stackBottom:
-	.skip 16384
+	.skip 8192
 stackTop:
 
 .section .text