diff --git a/src/cmd/link/internal/mips64/asm.go b/src/cmd/link/internal/mips64/asm.go
index d690a626dba6a0..d91fc6f98b0265 100644
--- a/src/cmd/link/internal/mips64/asm.go
+++ b/src/cmd/link/internal/mips64/asm.go
@@ -85,7 +85,7 @@ func gentext_noos(ctxt *ld.Link, ldr *loader.Loader) {
 	// search for user defined ISRs: //go:linkname functionName IRQ%d_Handler
 	// This code tries to keep runtime.vectors small, by cutting off all irq
 	// at the end that point to runtime.unhandledExternalInterrupt.
-	var irqHandlers [5]loader.Sym
+	var irqHandlers [8]loader.Sym
 	irqNum := 1
 	for i := 1; i < len(irqHandlers); i++ {
 		s := lookupFuncSym(ldr, ld.InterruptHandler(i))
diff --git a/src/runtime/rt0_noos_mips64.s b/src/runtime/rt0_noos_mips64.s
index f3f3aa665b032d..facd3026b897eb 100644
--- a/src/runtime/rt0_noos_mips64.s
+++ b/src/runtime/rt0_noos_mips64.s
@@ -16,6 +16,10 @@ TEXT runtime·_rt0_mips64_noos1(SB),NOSPLIT|NOFRAME,$0
 	// Store RAM size in a register not used by memclrNoHeapPointers
 	MOVV R4, R16
 
+	// Make sure the MIPS64X struct is initialized before calling
+	// memclrNoHeapPointers.
+	MOVBU	R0, internal∕cpu·MIPS64X+const_offsetMIPS64XHasMSA(SB)
+
 	// Clear .bss, .noptrbss and unallocated memory.
 	SUBU $16, R29
 
@@ -45,6 +49,7 @@ TEXT runtime·_rt0_mips64_noos1(SB),NOSPLIT|NOFRAME,$0
 	// Load interrupt vector
 	MOVW $runtime·intvector(SB), R8
 	MOVW $0xa0000000, R9
+	MOVW $0x80000000, R12
 	MOVW $4, R10
 loop:
 	MOVW (R8), R11
@@ -52,12 +57,13 @@ loop:
 	MOVW R11, 0x80(R9)
 	MOVW R11, 0x100(R9)
 	MOVW R11, 0x180(R9)
-	CACHE HIT_INVALIDATE_I, 0(R9)
-	CACHE HIT_INVALIDATE_I, 0x80(R9)
-	CACHE HIT_INVALIDATE_I, 0x100(R9)
-	CACHE HIT_INVALIDATE_I, 0x180(R9)
+	CACHE HIT_INVALIDATE_I, 0(R12)
+	CACHE HIT_INVALIDATE_I, 0x80(R12)
+	CACHE HIT_INVALIDATE_I, 0x100(R12)
+	CACHE HIT_INVALIDATE_I, 0x180(R12)
 	ADD $4, R8
 	ADD $4, R9
+	ADD $4, R12
 	ADDU $-1, R10
 	BGTZ R10,loop
 
@@ -101,13 +107,14 @@ TEXT runtime·rt0_go(SB),NOSPLIT|NOFRAME|TOPFRAME,$0
 	MOVV  $runtime·nodmaend(SB), R11
 	SUB   $SIGNAL_STACK_SIZE, R9
 
-	SUB   $32, R29
+	SUB   $48, R29
 	MOVV  R8, 8(R29)
 	MOVV  R9, 16(R29)
 	MOVV  R10, 24(R29)
 	MOVV  R11, 32(R29)
+	MOVV  R0, 40(R29)
 	JAL   runtime·meminit(SB)
-	ADD   $32, R29
+	ADD   $48, R29
 
 	// initialize noos tasker and Go scheduler
 	JAL   runtime·taskerinit(SB)
@@ -153,10 +160,9 @@ TEXT runtime·rt0_go(SB),NOSPLIT|NOFRAME|TOPFRAME,$0
 	ADD   $16, R29
 
 	// enable interrupts
-	// TODO where to enable interupts correctly?
 	MOVW R0, M(C0_COMPARE)
 	MOVW M(C0_SR), R8
-	OR   $(SR_IE|INTR_SW|INTR_EXT), R8
+	OR   $(SR_IE|INTR_SW), R8
 	MOVW R8, M(C0_SR)
 
 	// start this M
diff --git a/src/runtime/tasker_noos_mips64.go b/src/runtime/tasker_noos_mips64.go
index cebc3539e52df8..e583a3a3f32740 100644
--- a/src/runtime/tasker_noos_mips64.go
+++ b/src/runtime/tasker_noos_mips64.go
@@ -24,15 +24,15 @@ import (
 
 // See saveGPRS and saveFPRS
 const (
-	numGPRS = 28
+	numGPRS = 27
 	numFPRS = 33
 )
 
 type mOS struct {
 	// thread context
-	gprs            [numGPRS]uintptr
-	fprs            [numFPRS]float64
-	sp, fp, ra, epc uintptr
+	gprs                 [numGPRS]uintptr
+	fprs                 [numFPRS]float64
+	sp, fp, ra, epc, tmp uintptr
 }
 
 var (
@@ -112,7 +112,10 @@ func syscachemaint(op int, p unsafe.Pointer, size int) {
 	}
 }
 
-var highPrioIRQMask uint32
+var (
+	globalIRQMask   uint32
+	highPrioIRQMask uint32
+)
 
 func sysirqctl(irq, ctl, ctxid int) (enabled, prio, errno int) {
 	if uint(irq) > 8 { // TODO PIC dependent
@@ -132,14 +135,14 @@ func sysirqctl(irq, ctl, ctxid int) (enabled, prio, errno int) {
 		} else if ctl > 0 {
 			atomic.Or32(&highPrioIRQMask, irqMask) // set prio to high
 		}
-		creg.STATUS.SetBits(irqMask)
+		atomic.Or32(&globalIRQMask, irqMask)
 	case ctl == -2: // disable IRQ
-		creg.STATUS.ClearBits(irqMask)
+		atomic.And32(&globalIRQMask, ^irqMask)
 	default: // -3, IRQ status
 		if irqMask&atomic.Load(&highPrioIRQMask) != 0 {
 			prio = 1
 		}
-		if creg.STATUS.LoadBits(irqMask) != 0 {
+		if atomic.Load(&globalIRQMask)&irqMask != 0 {
 			enabled = 1
 		}
 	}
diff --git a/src/runtime/tasker_noos_mips64.s b/src/runtime/tasker_noos_mips64.s
index a7c33db906cfc8..672b0865ba6303 100644
--- a/src/runtime/tasker_noos_mips64.s
+++ b/src/runtime/tasker_noos_mips64.s
@@ -46,7 +46,8 @@
 #define _lr        (0*8)
 #define _mstatus   (1*8)
 #define _mepc      (2*8)
-#define excCtxSize (3*8)
+#define _mregtmp   (3*8)
+#define excCtxSize (4*8)
 
 
 // This will be copied into the processor's general exception vector.  Since the
@@ -69,6 +70,9 @@ TEXT runtime·intvector(SB),NOSPLIT|NOFRAME,$0
 // Only syscalls and interrupts are handled at the moment, all other exceptions
 // are fatal.
 TEXT runtime·exceptionHandler(SB),NOSPLIT|NOFRAME,$0
+	// Be especially careful to not clobber REGTMP with multi-instruction
+	// statements until it's saved on the stack.
+
 	// Determine caller stack
 	MOVV  $·cpu0(SB), R26
 	BNE   R26, g, fromThread
@@ -89,6 +93,7 @@ fromThread:
 fromHandler:
 	// Save exception context on ISR stack
 	SUB   $excCtxSize, R29
+	MOVV  R23, _mregtmp(R29) // R23 (REGTMP) is now free for use
 	OR    $1, R31, R26 // Encode smallCtx flag in lr
 	MOVV  R26, _lr(R29) // R29 is now free for use
 	MOVV  M(C0_SR), R26
@@ -170,7 +175,8 @@ TEXT runtime·syscallHandler(SB),NOSPLIT|NOFRAME,$0
 
 	MOVV  _lr(R29), R3
 	MOVV  R3, (m_mOS+mOS_ra)(R2)
-
+	MOVV  _mregtmp(R29), R3
+	MOVV  R3, (m_mOS+mOS_tmp)(R2)
 	MOVV  _mepc(R29), R3
 	AND   $~1, R3  // Remove fromHandler flag from epc
 	MOVV  R3, (m_mOS+mOS_epc)(R2)
@@ -184,7 +190,7 @@ TEXT runtime·syscallHandler(SB),NOSPLIT|NOFRAME,$0
 
 currentStack:
 	BGTZ  R4, badSyscall // slow syscall from handler
-	ADD   $excCtxSize, R29, R1 // duffcopy src handler
+	ADD   $excCtxSize, R29, R1 // duffcopy src
 
 duffcopy:
 	// 3 extra registers to preserve src, dst and size of result
@@ -249,6 +255,9 @@ TEXT runtime·softwareInterruptHandler(SB),NOSPLIT|NOFRAME,$0
 	// Save thread context in mOS
 	MOVV  (cpuctx_exe)(g), R27
 
+	MOVV  _mregtmp(R29), R26
+	MOVV  R26, (m_mOS+mOS_tmp)(R27)
+
 	MOVV  _lr(R29), R26
 	AND   $~1, R26  // Remove smallCtx flag from lr
 	MOVV  R26, (m_mOS+mOS_ra)(R27)
@@ -287,6 +296,10 @@ TEXT runtime·enterScheduler(SB),NOSPLIT|NOFRAME,$0
 
 	// Restore mstatus from exception context
 	MOVV  _mstatus(R29), R1
+	AND   $~INTR_EXT, R1
+	MOVW  ·globalIRQMask(SB), R2
+	AND   $INTR_EXT, R2
+	OR    R2, R1
 	MOVV  R1, M(C0_SR)
 	ADD   $excCtxSize, R29
 
@@ -311,8 +324,8 @@ smallCtx:
 	MOVV  (m_mOS+mOS_ra)(R27), R31
 	MOVV  (m_mOS+mOS_epc)(R27), R26
 	MOVV  R26, M(C0_EPC)
-	MOVV  $~1, R27
-	AND   R27, R31 // Remove smallCtx flag
+	AND   $~1, R31 // Remove smallCtx flag
+	MOVV  (m_mOS+mOS_tmp)(R27), R23
 
 	ERET
 
@@ -406,28 +419,42 @@ fatal:
 
 TEXT runtime·exceptionReturn(SB),NOSPLIT|NOFRAME,$0
 	MOVV  _mstatus(R29), R26
+	AND   $~INTR_EXT, R26
+	MOVW  ·globalIRQMask(SB), R27
+	AND   $INTR_EXT, R27
+	OR    R27, R26
 	MOVV  R26, M(C0_SR)
-	MOVV  _lr(R29), R26
-	MOVV  $~1, R27
-	AND   R27, R26, R31 // Remove smallCtx flag from lr
+	MOVV  _lr(R29), R31
+	AND   $~1, R31 // Remove smallCtx flag from lr
 	MOVV  _mepc(R29), R26
-	MOVV  $~1, R27
-	AND   R26, R27  // Remove fromHandler flag from EPC
+	AND   $~1, R26, R27  // Remove fromHandler flag from EPC
 	MOVV  R27, M(C0_EPC)
 
-	MOVV  $1, R27
-	AND   R26, R27
+	AND   $1, R26, R27
 
-	ADD   $excCtxSize, R29
+	// Don't restore interrupt mask or switch stacks yet if we were called
+	// from handler
+	BNE   R27, R0, fromHandler
 
-	// Don't switch stacks yet if we were called from handler
-	BNE   R27, R0, return
+	MOVW  M(C0_SR), R26
+	AND   $~INTR_EXT, R26
+	MOVW  ·globalIRQMask(SB), R27
+	AND   $INTR_EXT, R27
+	OR    R27, R26
+	MOVW  R26, M(C0_SR)
 
+	MOVV  _mregtmp(R29), R23
+	ADD   $excCtxSize, R29
 	MOVV  $·cpu0(SB), R26
 	MOVV  (g_sched+gobuf_sp)(R26), R29
 	MOVV  (g_sched+gobuf_g)(R26), g
 
-return:
+	ERET
+
+fromHandler:
+	MOVV  _mregtmp(R29), R23
+	ADD   $excCtxSize, R29
+
 	ERET
 
 
@@ -460,29 +487,25 @@ TEXT ·saveGPRs(SB),NOSPLIT|NOFRAME,$0
 	MOVV R20, 152(R26)
 	MOVV R21, 160(R26)
 	MOVV R22, 168(R26)
-	MOVV R23, 176(R26)
-	MOVV R24, 184(R26)
-	MOVV R25, 192(R26)
-	MOVV RSB, 200(R26)
+	MOVV R24, 176(R26)
+	MOVV R25, 184(R26)
+	MOVV RSB, 192(R26)
 	MOVV HI, R1
-	MOVV R1, 208(R26)
+	MOVV R1, 200(R26)
 	MOVV LO, R1
-	MOVV R1, 216(R26)
+	MOVV R1, 208(R26)
 	RET
 
 
-// R26 must point to stored gprs.  Only use R26, R27 after restoring.  Be
-// especially careful and look at the disassembly;  The assembler might decide
-// to use R16-R23 for you.
+// R26 must point to stored gprs.  Only use R26, R27 after restoring.
 TEXT ·restoreGPRs(SB),NOSPLIT|NOFRAME,$0
-	MOVV 216(R26), R1
-	MOVV R1, LO
 	MOVV 208(R26), R1
+	MOVV R1, LO
+	MOVV 200(R26), R1
 	MOVV R1, HI
-	MOVV 200(R26), RSB
-	MOVV 192(R26), R25
-	MOVV 184(R26), R24
-	MOVV 176(R26), R23
+	MOVV 192(R26), RSB
+	MOVV 184(R26), R25
+	MOVV 176(R26), R24
 	MOVV 168(R26), R22
 	MOVV 160(R26), R21
 	MOVV 152(R26), R20