1 files changed, 27 insertions, 2 deletions

diff --git a/src/start.s b/src/start.s
index 0fd2a5f..b142397 100644
--- a/src/start.s
+++ b/src/start.s
@@ -3,8 +3,33 @@
 .global _start
 
 _start:
-    ldr r3, =main
-    blx r3
+    // Stop all cores except one.
+    mrs     x0, mpidr_el1
+    and     x0, x0, #0xFF
+    cbz     x0, master
+    b halt
+
+// Helper function to clear x1 bytes starting at the x0 memory address.
+memzero:
+    str xzr, [x0], #8
+    subs x1, x1, #8
+    b.gt memzero
+    ret
+
+master:
+    // Clear bss.
+    ldr x0, =__bss_start
+    ldr x1, =__bss_size
+    sub x1, x1, x0
+    bl memzero
+
+    // Set stack before our code.
+    ldr     x0, =_start
+    mov     sp, x0
+
+    // Start C code, should not return.
+    bl      main
+    b       halt
 
 halt:
     wfe