Add ecall/ebreak

firmware/link.ld

@@ -15,12 +15,6 @@ SECTIONS {
         . = ALIGN(4);
     }
 
-    . = 0x20000;
-
-    .vectors : {
-        *(.text.vectors)
-    }
-
     . = 0x20000000;
 
     .data : {
@@ -32,4 +26,8 @@ SECTIONS {
     .bss : {
         *(.bss*)
     }
+
+    . = 0x20400000;
+
+    .end : {}
 }

firmware/src/entry.S

@@ -4,19 +4,32 @@
 .option push
 .option norvc
 __entry:
+__reset:        j fw_entry
+__exception:    j fw_exception_entry
+
+fw_entry:
     la sp, stack_top
     jal {firmware_main}
+fw_exception_entry:
+    mv tp, sp
+    la sp, exception_stack_top
+    jal {firmware_exception}
+    j .
 
 .option pop
 .popsection // .text.entry
 
-.pushsection .text.vectors
+.pushsection .text.vectors, "ax"
+.global __vector
 __vector:
     j .
 .popsection // .text.vectors
 
 .pushsection .bss
 stack_bottom:
-    .skip 2048
+    .skip 65536
 stack_top:
+exception_stack_bottom:
+    .skip 65536
+exception_stack_top:
 .popsection // .bss

firmware/src/main.rs

@@ -35,8 +35,18 @@ unsafe extern "C" fn firmware_main() -> ! {
     loop {
         // TODO pause/system/fence instruction not implemented
         // core::hint::spin_loop();
-        core::arch::asm!("nop");
+        core::arch::asm!("ebreak");
     }
 }
 
-global_asm!(include_str!("entry.S"), firmware_main = sym firmware_main);
+unsafe extern "C" fn firmware_exception() {
+    use fmt::Write;
+    let mut d = D;
+    writeln!(d, "In exception handler").ok();
+}
+
+global_asm!(
+    include_str!("entry.S"),
+    firmware_main = sym firmware_main,
+    firmware_exception = sym firmware_exception
+);