[Qemu-discuss] qemu-system-mips64el: dins instruction causes exception

[strefil]

I run simple program:

.set noreorder
.globl __start
__start:
        bal     begin
        nop
        dinsm   $3, $31, 0x0c, 0x19

$  qemu-system-mips64el -cpu 'MIPS64R2-generic' -nographic -machine
magnum -bios /tmp/dins.bin -d cpu

helper_raise_exception_err: 20 0
do_interrupt enter: PC ffffffffbfc00008 EPC 0000000000000000 reserved
instruction exception do_interrupt: PC ffffffffbfc00380 EPC
ffffffffbfc00008 cause 10 S 00400006 C 00000028 A 0000000000000000 D
0000000000000000 pc=0xffffffffbfc00380 HI=0x0000000000000000
LO=0x0000000000000000 ds 0018 0000000000000000 0 GPR00: r0
0000000000000000 at 0000000000000000 v0 0000000000000000 v1
0000000000000000 GPR04: a0 0000000000000000 a1 0000000000000000 a2
0000000000000000 a3 0000000000000000 GPR08: t0 0000000000000000 t1
0000000000000000 t2 0000000000000000 t3 0000000000000000 GPR12: t4
0000000000000000 t5 0000000000000000 t6 0000000000000000 t7
0000000000000000 GPR16: s0 0000000000000000 s1 0000000000000000 s2
0000000000000000 s3 0000000000000000 GPR20: s4 0000000000000000 s5
0000000000000000 s6 0000000000000000 s7 0000000000000000 GPR24: t8
0000000000000000 t9 0000000000000000 k0 0000000000000000 k1
0000000000000000 GPR28: gp 0000000000000000 sp 0000000000000000 s8
0000000000000000 ra ffffffffbfc00008 CP0 Status  0x00400006 Cause
0x00000028 EPC    0xffffffffbfc00008 Config0 0x80004482 Config1
0xfea3519b LLAddr 0x0000000000000000

AFAIK MIPS64R2 instruction dins should not cause exception.  Why
does it raised anyway?