From f8cc0d73afe12cc1c8dd1600a28ff4634decf617 Mon Sep 17 00:00:00 2001
From: cheapie <cheapiephp@gmail.com>
Date: Sun, 8 Nov 2026 07:38:17 -0600
Subject: Add Smrnmi

---
 assembly/crosswalk/crosswalk.S |  1 +
 assembly/multitask/multitask.S |  1 +
 assembly/rrxing2/rrxing2.S     | 19 ++++++++++++++++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

(limited to 'assembly')

diff --git a/assembly/crosswalk/crosswalk.S b/assembly/crosswalk/crosswalk.S
index 86a0813..4baeaa8 100644
--- a/assembly/crosswalk/crosswalk.S
+++ b/assembly/crosswalk/crosswalk.S
@@ -1,3 +1,4 @@
+csrsi mnstatus,8 # Set NMIE so that interrupts can work (not actually setting up a real NMI handler)
 la t0,handler
 csrw mtvec,t0 # Set up trap handler
 li t0,0x400
diff --git a/assembly/multitask/multitask.S b/assembly/multitask/multitask.S
index e46dd81..29df46c 100644
--- a/assembly/multitask/multitask.S
+++ b/assembly/multitask/multitask.S
@@ -1,3 +1,4 @@
+csrsi mnstatus,8 # Set NMIE so that interrupts can work (not actually setting up a real NMI handler)
 la t0,handler
 csrw mtvec,t0 # Set trap handler address and mode (0/direct)
 li t0,0x400
diff --git a/assembly/rrxing2/rrxing2.S b/assembly/rrxing2/rrxing2.S
index c94edc0..bb2c4dc 100644
--- a/assembly/rrxing2/rrxing2.S
+++ b/assembly/rrxing2/rrxing2.S
@@ -8,6 +8,9 @@ j _start
 .include "util.S"
 
 _start:
+la t0,nmihandler
+csrw 0xbc0,t0 # Set up RNMI handler
+csrsi mnstatus,8 # Turn on NMIE
 li t0,0x400
 csrs mseccfg,t0 # Turn on MLPE (enable Zicfilp)
 li sp,0x10000 # Set up stack pointer
@@ -187,6 +190,19 @@ ecall # Tell the user
 li a7,10
 ecall # Then halt
 
+.align 2
+nmihandler:
+li a7,4
+la a0,uinmi
+ecall # Display NMI message
+
+csrr a0,mncause # Read what the cause was
+li a7,1
+ecall # Tell the user
+
+li a7,10
+ecall # Then halt
+
 states: .word destate0,destate1,destate2,destate3,destate4,destate5,destate6,0,0,0,0,0,0,0,0,0
 .word ukstate0,ukstate1,ukstate2,ukstate3,ukstate4,ukstate5,ukstate6,ukstate7,0,0,0,0,0,0,0,0
 .word usstate0,usstate1,usstate2,usstate3,usstate4,0,0,0,0,0,0,0,0,0,0,0
@@ -364,7 +380,8 @@ activetime: .byte 15
 extensiontime: .byte 25
 traincounter: .word 0
 
-uiunimplementedtrap: .asciz "Unimplemented trap!\nmcause: "
+uiunimplementedtrap: .asciz "\nUnimplemented trap!\nmcause: "
+uinmi: .asciz "\nUnexpected NMI!\nmncause: "
 channelbuf: .skip 16
 msgbuf: .skip 16
 lightchannel: .asciz "light"
-- 
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