Re: [Qemu-devel] Decode of MIPS DMFC0 and DMTC0

[Thiemo Seufer]

Dirk Behme wrote:
> Hi,
> 
> looking into target-mips/translate.c, in function 
> decode_opc() OPC_DMFC0 and OPC_DMTC0 are mapped to gen_cp0() 
> if MIPS64 is enabled:
> 
> case OPC_CP0:
>         op1 = MASK_CP0(ctx->opcode);
>         switch (op1) {
>         case OPC_MFC0:
>         case OPC_MTC0:
> #ifdef MIPS_HAS_MIPS64
>         case OPC_DMFC0:
>         case OPC_DMTC0:
> #endif
>             gen_cp0(ctx, op1, rt, rd);
>             break;
> 
> But looking into gen_cp0() in same file, there is no case 
> statement for OPC_DMFC0 and OPC_DMTC0. Looks to me that this 
> results in a RI exception.
> 
> Do I overlook anything here or is DMFC0/DMTC0 decoding 
> missing in gen_cp0()?

You are right. Note that the MIPS64 support is highly experimental at
this point, there is e.g. no proper 64bit FPU support, and no 64bit
addressing.


Thiemo