feat(loader, kernel): impl part of loader and initialize kernel structure

arch/x86_64/boot/idt.zig

@@ -0,0 +1,23 @@
+const desc = @import("arch").desc;
+const mem = @import("arch").mem;
+const TrapType = @import("arch").trap.TrapType;
+extern const __KERNEL_CS: u8;
+
+var idt_table: [256]desc.IdtEntry align(mem.PAGE_SIZE) = .{.{}} ** 256;
+extern const boot_page_fault: u8;
+extern const boot_nmi: u8;
+
+fn setIdtEntry(vec: usize, handler: anytype) void {
+    var entry = desc.IdtEntry{};
+    entry.setOffset(@intFromPtr(handler));
+    entry.selector = @intFromPtr(&__KERNEL_CS);
+    entry.gate_type = .trap;
+    entry.present = 1;
+    idt_table[vec] = entry;
+}
+
+export fn loadLoaderIdt() void {
+    setIdtEntry(TrapType.PF, &boot_page_fault);
+    setIdtEntry(TrapType.NMI, &boot_nmi);
+    desc.loadIdt(&idt_table);
+}