diff --git a/Makefile b/Makefile
index 14ca555..1363245 100644
--- a/Makefile
+++ b/Makefile
@@ -168,8 +168,6 @@ QEMUOPTS += -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
 qemu: $K/kernel fs.img
 	$(QEMU) $(QEMUOPTS)
 
-kernel: $K/kernel
-
 .gdbinit: .gdbinit.tmpl-riscv
 	sed "s/:1234/:$(GDBPORT)/" < $^ > $@
 
diff --git a/kernel/riscv.h b/kernel/riscv.h
index 47d5397..c934309 100644
--- a/kernel/riscv.h
+++ b/kernel/riscv.h
@@ -429,16 +429,6 @@ typedef u64 *pagetable_t; // 512 PTEs
 /**
  * Page Table Entry Flags
  */
-/** Valid */
-#define PTE_V (1L << 0)
-/** Readable */
-#define PTE_R (1L << 1)
-/** Writable */
-#define PTE_W (1L << 2)
-/** Executable */
-#define PTE_X (1L << 3)
-/** User-accessible */
-#define PTE_U (1L << 4)
 
 #define PTE_V (1L << 0) /** PTE Valid */
 #define PTE_R (1L << 1) /** PTE Readable */
diff --git a/kernel/vm.c b/kernel/vm.c
index dc33f30..af3ff45 100644
--- a/kernel/vm.c
+++ b/kernel/vm.c
@@ -12,7 +12,7 @@ extern char etext[]; // kernel.ld sets this to end of kernel code.
 
 extern char trampoline[]; // trampoline.S
 
-/** Make a direct-map page table for the kernel. */
+// Make a direct-map page table for the kernel.
 pagetable_t
 kvmmake(void)
 {
@@ -49,17 +49,15 @@ kvmmake(void)
   return kpgtbl;
 }
 
-/** Initialize the one kernel_pagetable */
+// Initialize the one kernel_pagetable
 void
 kvminit(void)
 {
   kernel_pagetable = kvmmake();
 }
 
-/**
- * Switch h/w page table register to the kernel's page table,
- * and enable paging.
- */
+// Switch h/w page table register to the kernel's page table,
+// and enable paging.
 void
 kvminithart()
 {