Re: [Qemu-devel] [PATCH] hw/scsi/lsi53c895a: add support for additional diag / debug registers

[Paolo Bonzini]

On 12/01/2015 10:45, Peter Lieven wrote:
> Some ancient Linux kernels read from registers 0x09 and 0x3c-3f during
> boot. According to the spec these registers are for diag and debug
> purposes only. If they are absend qemu aborts on read.
> 
> Signed-off-by: Peter Lieven <address@hidden>
> ---
>  hw/scsi/lsi53c895a.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
> index ec92048..db7d4b8 100644
> --- a/hw/scsi/lsi53c895a.c
> +++ b/hw/scsi/lsi53c895a.c
> @@ -277,6 +277,7 @@ typedef struct {
>      uint32_t csbc;
>      uint32_t scratch[18]; /* SCRATCHA-SCRATCHR */
>      uint8_t sbr;
> +    uint32_t adder;
>  
>      /* Script ram is stored as 32-bit words in host byteorder.  */
>      uint32_t script_ram[2048];
> @@ -1389,6 +1390,7 @@ again:
>                  switch ((insn >> 27) & 7) {
>                  case 0: /* Jump */
>                      DPRINTF("Jump to 0x%08x\n", addr);
> +                    s->adder = addr;
>                      s->dsp = addr;
>                      break;
>                  case 1: /* Call */
> @@ -1513,6 +1515,8 @@ static uint8_t lsi_reg_readb(LSIState *s, int offset)
>          return 0x7f;
>      case 0x08: /* Revision ID */
>          return 0x00;
> +    case 0x09: /* SOCL */
> +        return s->socl;
>      case 0xa: /* SSID */
>          return s->ssid;
>      case 0xb: /* SBCL */
> @@ -1577,6 +1581,8 @@ static uint8_t lsi_reg_readb(LSIState *s, int offset)
>          return s->sbr;
>      case 0x3b: /* DCNTL */
>          return s->dcntl;
> +    /* ADDER Output (Debug of relative jump address) */
> +    CASE_GET_REG32(adder, 0x3c)
>      case 0x40: /* SIEN0 */
>          return s->sien0;
>      case 0x41: /* SIEN1 */
> 

Thanks!

Paolo