kprintf and kprint_float

src/boot/entry.S

@@ -4,12 +4,16 @@ _start:
     la sp, stack_top      # Set up the stack pointer
     la t0, trap_entry     # Set up the trap handler
     csrw mtvec, t0        # Set the trap vector to our trap handler
+    li t0, 0x00006000     # Load the mask for FS bits. enable float
+    csrs mstatus, t0      # Set the FS bits to 11 (Dirty/Initial). enable float
     call kmain            # Jump to our C code
 loop:
     wfi                   # Wait for Interrupt (saves CPU)
     j loop                # Infinite loop if C returns
 .align 4
 trap_entry:
+    csrr a0, mcause    # Argument 1: mcause
+    csrr a1, mepc      # Argument 2: mepc
     j handle_trap
 .section .bss
 .align 16