Hardened paging into a real VMM

src/main.zig

@@ -86,10 +86,11 @@ fn kmain(boot_info: *const BootInfo) noreturn {
     if (f2) |p| pmm.free(p);
     con.print("  after free : {d} frames free\n", .{pmm.stats().free_frames});
 
-    // Switch off the firmware's page tables onto our own.
-    arch.enablePaging(pmm.alloc);
+    // Switch off the firmware's page tables onto our own (with real permissions).
+    arch.enablePaging(pmm.alloc, boot_info);
     con.print("\ndanos: paging enabled\n", .{});
     con.print("  page tables: CR3 = 0x{x:0>16}\n", .{arch.readCr3()});
+    con.print("  kernel segs: {d} (mapped with W^X permissions)\n", .{boot_info.kernel_segment_count});
 
     // Start the timer and unmask interrupts — the kernel now has a heartbeat.
     arch.startTimer();