Re: [Qemu-devel] r4k doesn't support movz

[Jia Liu]

Hi Eric&Zhang,

Nope, you two are wrong. Aurelien is right.
Let me show you the code.

1, qemu/hw/mips_r4k.c --    for    qemu-system-mips4el -M mips    board.
void mips_r4k_init (...)
{
...
    /* init CPUs */
    if (cpu_model == NULL) {
#ifdef TARGET_MIPS64
        cpu_model = "R4000";
#else
        cpu_model = "24Kf";
#endif
    }
...
}

OK, we all see the CPU is R4000 when we config qemu to MIPS64.

2, http://en.wikipedia.org/wiki/R4000
The R4000 is a microprocessor developed by MIPS Computer Systems that
implemented the MIPS III instruction set architecture (ISA).
Officially announced on 1 October 1991

3, qemu/target-mips/translate_init.c
#if defined(TARGET_MIPS64)
    {
        .name = "R4000",
...
        .insn_flags = CPU_MIPS3,
...
    },

we can see R400 has MIPS3 insns.

4, qemu/target-mips/mips_defs.h
#define         ISA_MIPS3       0x00000004
#define         ISA_MIPS4       0x00000008

#define         CPU_MIPS3       (CPU_MIPS2 | ISA_MIPS3)
#define         CPU_MIPS4       (CPU_MIPS3 | ISA_MIPS4)

we can see it, CPU_MIPS4 holds ISA_MIPS4 and all CPU_MIPS3 insns,
but CPU_MIPS3 doesn't hold ISA_MIPS4 insns.

5, qemu/target-mips/translate.c
        case OPC_MOVN:         /* Conditional move */
        case OPC_MOVZ:
            check_insn(env, ctx, ISA_MIPS4 | ISA_MIPS32 |
                                 INSN_LOONGSON2E | INSN_LOONGSON2F);
Here is NO MIPS3 support, that is R4000 does NOT support Conditional moves.



If this is not enough, all right, let check binutils file.

binutils/opcodes/mips-opc.c
#define I3      INSN_ISA3
#define I4      INSN_ISA4

{"movz",    "d,v,t",    0x0000000a, 0xfc0007ff, WR_d|RD_s|RD_t,
        0,              I4_32|IL2E|IL2F },

So, we all see it. movz is not a MIPS3/R4000 instruction.



Regards,
Jia.

On Sat, May 19, 2012 at 9:02 AM, Johnson, Eric <address@hidden> wrote:
> Hi Zhi-zhou Zhang,
>
>
>
> You are correct.  This should not be a reserved instruction exception on
> MIPS64 (nor should MOVN).
>
>
>
> -Eric
>
>
>
> From: address@hidden
> [mailto:address@hidden On Behalf Of Zhi-zhou
> Zhang
> Sent: Friday, May 18, 2012 4:39 AM
> To: address@hidden
> Cc: address@hidden
> Subject: [Qemu-devel] r4k doesn't support movz
>
>
>
> Hi Aurelien,
>
>
>
> I found that when qemu-system-mips64el executed 'movz' with -M mips, it
> would raise a reserved instruction exception.
>
> The mips spec describes movz as below:
>
>
>
> Mnemonic               Instructio                      Defined in MIPS ISA
>
> MOVZ            Move Conditional on Zero       MIPS32
>
>
>
> I think ISA-64 should support MIPS32 instructions for compatible. am I
> right?
>
>
>
> --
> Regards,
>
> Zhizhou Zhang
>
>