diff --git a/firmware/fw_base.S b/firmware/fw_base.S
index cdb15429..043de7d7 100644
--- a/firmware/fw_base.S
+++ b/firmware/fw_base.S
@@ -529,6 +529,45 @@ memcmp:
 	csrrw	tp, CSR_MSCRATCH, tp
 .endm
 
+.macro	TRAP_SAVE_AND_SETUP_SP_T0_NMI
+	/* Swap TP and MNSCRATCH (for RNMI) */
+	csrrw	tp, CSR_MNSCRATCH, tp
+
+	/* Save T0 in scratch space */
+	REG_S	t0, SBI_SCRATCH_TMP1_OFFSET(tp)
+
+	/*
+	 * Set T0 to appropriate exception stack
+	 *
+	 * Came_From_M_Mode = ((MNSTATUS.MNPP < PRV_M) ? 1 : 0) - 1;
+	 * Exception_Stack = TP ^ (Came_From_M_Mode & (SP ^ TP))
+	 */
+	csrr	t0, CSR_MNSTATUS
+	srl	t0, t0, 11		/* MNPP is at bits 11-12 */
+	and	t0, t0, PRV_M
+	slti	t0, t0, PRV_M
+	add	t0, t0, -1
+	xor	sp, sp, tp
+	and	t0, t0, sp
+	xor	sp, sp, tp
+	xor	t0, tp, t0
+
+	/* Save original SP on exception stack */
+	REG_S	sp, (SBI_TRAP_REGS_OFFSET(sp) - SBI_TRAP_CONTEXT_SIZE)(t0)
+
+	/* Set SP to exception stack and make room for trap context */
+	add	sp, t0, -(SBI_TRAP_CONTEXT_SIZE)
+
+	/* Restore T0 from scratch space */
+	REG_L	t0, SBI_SCRATCH_TMP1_OFFSET(tp)
+
+	/* Save T0 on stack */
+	REG_S	t0, SBI_TRAP_REGS_OFFSET(t0)(sp)
+
+	/* Swap TP and MNSCRATCH */
+	csrrw	tp, CSR_MNSCRATCH, tp
+.endm
+
 .macro	TRAP_SAVE_MEPC_MSTATUS have_mstatush
 	/* Save MEPC and MSTATUS CSRs */
 	csrr	t0, CSR_MEPC
@@ -543,6 +582,20 @@ memcmp:
 	.endif
 .endm
 
+.macro	TRAP_SAVE_MNEPC_MNSTATUS have_mstatush
+	/*
+	 * Save MNEPC and MNSTATUS CSRs (for RNMI)
+	 * Note: Trap context structure has generic field names (mepc, mstatus),
+	 * we store MN* CSR values into these same structure fields.
+	 */
+	csrr	t0, CSR_MNEPC
+	REG_S	t0, SBI_TRAP_REGS_OFFSET(mepc)(sp)
+	csrr	t0, CSR_MNSTATUS
+	REG_S	t0, SBI_TRAP_REGS_OFFSET(mstatus)(sp)
+	/* MNSTATUSH doesn't exist in SMRNMI spec */
+	REG_S	zero, SBI_TRAP_REGS_OFFSET(mstatusH)(sp)
+.endm
+
 .macro	TRAP_SAVE_GENERAL_REGS_EXCEPT_SP_T0
 	/* Save all general regisers except SP and T0 */
 	REG_S	zero, SBI_TRAP_REGS_OFFSET(zero)(sp)
@@ -606,12 +659,36 @@ memcmp:
 	CLEAR_MDT t0
 .endm
 
+.macro	TRAP_SAVE_NMI_INFO
+	/*
+	 * Save NMI trap info (MNCAUSE, no MNTVAL in spec)
+	 * Note: Trap info structure has generic field names (cause, tval, etc.),
+	 * we store MN* CSR values into these same structure fields.
+	 */
+	csrr	t0, CSR_MNCAUSE
+	REG_S	t0, (SBI_TRAP_REGS_SIZE + SBI_TRAP_INFO_OFFSET(cause))(sp)
+	/* MNTVAL doesn't exist in SMRNMI spec */
+	REG_S	zero, (SBI_TRAP_REGS_SIZE + SBI_TRAP_INFO_OFFSET(tval))(sp)
+	REG_S	zero, (SBI_TRAP_REGS_SIZE + SBI_TRAP_INFO_OFFSET(tval2))(sp)
+	REG_S	zero, (SBI_TRAP_REGS_SIZE + SBI_TRAP_INFO_OFFSET(tinst))(sp)
+	REG_S	zero, (SBI_TRAP_REGS_SIZE + SBI_TRAP_INFO_OFFSET(gva))(sp)
+
+	/* We are ready to take another trap, clear MDT */
+	CLEAR_MDT t0
+.endm
+
 .macro	TRAP_CALL_C_ROUTINE
 	/* Call C routine */
 	add	a0, sp, zero
 	call	sbi_trap_handler
 .endm
 
+.macro	TRAP_CALL_C_RNMI_ROUTINE
+	/* Call C routine */
+	add	a0, sp, zero
+	call	sbi_trap_rnmi_handler
+.endm
+
 .macro	TRAP_RESTORE_GENERAL_REGS_EXCEPT_A0_T0
 	/* Restore all general regisers except A0 and T0 */
 	REG_L	ra, SBI_TRAP_REGS_OFFSET(ra)(a0)
@@ -660,6 +737,19 @@ memcmp:
 	csrw	CSR_MEPC, t0
 .endm
 
+.macro	TRAP_RESTORE_MNEPC_MNSTATUS
+	/*
+	 * Restore MNSTATUS and MNEPC CSRs (for RNMI)
+	 * Note: Load from generic structure fields (mstatus, mepc) and
+	 * restore to NMI-specific CSRs (MNSTATUS, MNEPC).
+	 * No MNSTATUSH in SMRNMI spec.
+	 */
+	REG_L	t0, SBI_TRAP_REGS_OFFSET(mstatus)(a0)
+	csrw	CSR_MNSTATUS, t0
+	REG_L	t0, SBI_TRAP_REGS_OFFSET(mepc)(a0)
+	csrw	CSR_MNEPC, t0
+.endm
+
 .macro TRAP_RESTORE_A0_T0
 	/* Restore T0 */
 	REG_L	t0, SBI_TRAP_REGS_OFFSET(t0)(a0)
@@ -724,6 +814,37 @@ _trap_handler_hyp:
 
 	mret
 
+	.section .entry, "ax", %progbits
+	.align 3
+	.globl _trap_rnmi_handler
+_trap_rnmi_handler:
+	/*
+	 * NMI interrupt handler using MN* CSRs
+	 *
+	 * Context detection via MNPP (previous privilege mode):
+	 * - If MNPP < M-mode: use exception stack (TP)
+	 * - If MNPP == M-mode: use current stack (SP)
+	 * This handles nested interrupt cases.
+	 */
+	TRAP_SAVE_AND_SETUP_SP_T0_NMI
+
+	TRAP_SAVE_MNEPC_MNSTATUS 0
+
+	TRAP_SAVE_GENERAL_REGS_EXCEPT_SP_T0
+
+	TRAP_SAVE_NMI_INFO
+
+	TRAP_CALL_C_RNMI_ROUTINE
+
+	TRAP_RESTORE_GENERAL_REGS_EXCEPT_A0_T0
+
+	TRAP_RESTORE_MNEPC_MNSTATUS
+
+	TRAP_RESTORE_A0_T0
+
+	/* mnret - return from NMI (SMRNMI extension) */
+	.word 0x70200073
+
 	.section .entry, "ax", %progbits
 	.align 3
 	.globl _reset_regs
diff --git a/include/sbi/sbi_platform.h b/include/sbi/sbi_platform.h
index e65d9877..715df499 100644
--- a/include/sbi/sbi_platform.h
+++ b/include/sbi/sbi_platform.h
@@ -149,6 +149,10 @@ struct sbi_platform_operations {
 			unsigned long log2len);
 	/** platform specific pmp disable on current HART */
 	void (*pmp_disable)(unsigned int n);
+
+	/** platform specific Smrnmi NMI handler.
+	 *  Returns SBI_SUCCESS on success, error code if NMI cannot be handled. */
+	int (*rnmi_handler)(struct sbi_trap_context *tcntx);
 };
 
 /** Platform default per-HART stack size for exception/interrupt handling */
diff --git a/include/sbi/sbi_trap.h b/include/sbi/sbi_trap.h
index 731a0c98..091a2446 100644
--- a/include/sbi/sbi_trap.h
+++ b/include/sbi/sbi_trap.h
@@ -289,6 +289,8 @@ static inline void sbi_trap_set_context(struct sbi_scratch *scratch,
 
 struct sbi_trap_context *sbi_trap_handler(struct sbi_trap_context *tcntx);
 
+struct sbi_trap_context *sbi_trap_rnmi_handler(struct sbi_trap_context *tcntx);
+
 #endif
 
 #endif
diff --git a/lib/sbi/sbi_trap.c b/lib/sbi/sbi_trap.c
index f41db4d1..1e55b885 100644
--- a/lib/sbi/sbi_trap.c
+++ b/lib/sbi/sbi_trap.c
@@ -20,6 +20,7 @@
 #include <sbi/sbi_irqchip.h>
 #include <sbi/sbi_trap_ldst.h>
 #include <sbi/sbi_pmu.h>
+#include <sbi/sbi_platform.h>
 #include <sbi/sbi_scratch.h>
 #include <sbi/sbi_sse.h>
 #include <sbi/sbi_timer.h>
@@ -375,3 +376,41 @@ trap_done:
 	sbi_trap_set_context(scratch, tcntx->prev_context);
 	return tcntx;
 }
+
+/**
+ * Default Resumable NMI (RNMI) handler
+ *
+ * This function is called from the _trap_rnmi_handler assembly code.
+ * It provides a simple wrapper that calls the platform-specific
+ * NMI handler if registered. If no handler is registered, it prints
+ * diagnostic information and hangs, similar to unhandled traps.
+ *
+ * Note: The trap context stores NMI CSR values (MNCAUSE, MNEPC, MNSTATUS)
+ * in the generic trap context fields (cause, mepc, mstatus).
+ *
+ * @param tcntx Pointer to trap context (saved on stack)
+ * @return Same trap context pointer (needed for restore macros)
+ */
+struct sbi_trap_context *sbi_trap_rnmi_handler(struct sbi_trap_context *tcntx)
+{
+	int rc;
+	const struct sbi_platform *plat = sbi_platform_thishart_ptr();
+	const struct sbi_platform_operations *ops = sbi_platform_ops(plat);
+
+	/* Call platform-specific NMI handler if registered */
+	if (ops && ops->rnmi_handler) {
+		rc = ops->rnmi_handler(tcntx);
+		if (rc) {
+			/* Platform handler failed to handle NMI */
+			sbi_trap_error("platform NMI handler failed", rc, tcntx);
+		}
+		return tcntx;
+	}
+
+	/* No platform handler - treat as unhandled NMI */
+	sbi_trap_error("unhandled NMI (no platform rnmi_handler)",
+		       SBI_ENOTSUPP, tcntx);
+
+	/* Never returns */
+	return tcntx;
+}