Changeset 281 for trunk

Timestamp:

Dec 8, 2012, 4:59:50 PM (12 years ago)

Author:

bouyer

Message:

Keep BEV bit set in STATUS register, and add an exception handler at
0xbfc0380. This handler just prints STATUS, CAUSE and EPC register and
stalls (does an infinite loop).

Location:

trunk/softs/tsar_boot

Files:

• Makefile (modified) (1 diff)
• reset.S (modified) (2 diffs)

trunk/softs/tsar_boot/Makefile

@@ -42 +42 @@
 C_SRCS     += boot_tty.c
 C_SRCS     += boot_loader_entry.c
+C_SRCS     += exceptions.c
 
 OBJS       := $(subst .s,.o,$(S_SRCS))

trunk/softs/tsar_boot/reset.S

@@ -42 +42 @@
 
 _boot:
-    # Disable interruptions
+    # Disable interruptions, keep STATUSbev enabled
 
-    mtc0    $0,     $12
+    la      $4,     (1 << 22)
+    mtc0    $4,     $12
 
     # computes proc_id, local_id, cluster_id, and cluster_increment
@@ -124 +125 @@
     jr      $2
 
+# exeption entry point
+.org    0x0380
+_exep:
+    mfc0    $4, $12, 0  # first arg is status
+    mfc0    $5, $13, 0  # second arg is cause
+    mfc0    $6, $14, 0  # third argc is epc
+    nop
+    j       handle_exept
+    nop
+
     .end    boot