Halt syscall and userspace util. Mapped qemu power.

kernel/memlayout.h

@@ -23,6 +23,8 @@
 #define UART0     0x10000000L
 #define UART0_IRQ 10
 
+#define QEMU_POWER 0x100000
+
 // virtio mmio interface
 #define VIRTIO0     0x10001000
 #define VIRTIO0_IRQ 1

kernel/sysproc.c

@@ -100,5 +100,6 @@ sys_trace(void)
 void
 sys_halt(void)
 {
-  /* TODO: Implement sys_halt */
+  (*(volatile u32 *)QEMU_POWER) = 0x5555;
+  panic("sys_poweroff");
 }

kernel/vm.c

@@ -21,6 +21,9 @@ kvmmake(void)
   kpgtbl = (pagetable_t)kalloc();
   memset(kpgtbl, 0, PGSIZE);
 
+  // Map qemu
+  kvmmap(kpgtbl, QEMU_POWER, QEMU_POWER, PGSIZE, PTE_R | PTE_W);
+
   // uart registers
   kvmmap(kpgtbl, UART0, UART0, PGSIZE, PTE_R | PTE_W);
 

user/halt.c

@@ -4,6 +4,7 @@
 int
 main(int argc, char *argv[])
 {
+  printf("System powering down...\n");
   halt();
   return 0;
 }