Load the TSS.

src/kernel/arch/x86/gdt.c

@@ -58,9 +58,16 @@ void gdt_install() {
 	// user
 	gdt_entry_set(&gdt[3], 0, 0xFFFFFFFF, 0xFA, 0xCF);
 	gdt_entry_set(&gdt[4], 0, 0xFFFFFFFF, 0xF2, 0xCF);
+
 	// TSS
+	tss.ss0 = 0x10;
+	// TODO: set esp0 for system interrupts
+	tss.iopb = sizeof(tss);
 	gdt_entry_set(&gdt[5], (uint32_t)&tss,
 			sizeof(tss), 0x89, 0x40);
 
 	gdt_flush(&gdtr);
+
+	// load the TSS
+	tss_load();
 }

src/kernel/arch/x86/gdt.h

@@ -21,6 +21,7 @@
 #include "structs.h"
 
 extern void gdt_flush(struct segreg *gdtr);
+extern void tss_load();
 void gdt_entry_set(struct segdesc *entry, uint32_t base,
 		uint32_t limit, uint8_t access, uint8_t gran);
 void gdt_install();

src/kernel/arch/x86/gdt.s

@@ -35,3 +35,13 @@ gdt_flush:
 gdt_flush_end:
 	popl %ebp
 	ret
+
+.global tss_load
+.type tss_load,@function
+tss_load:
+	pushl %ebp
+	movl %esp, %ebp
+	movw $0x28, %ax
+	ltr %ax
+	popl %ebp
+	ret