Re: [PATCH v2] target/m68k: only change valid bits in CACR

[Thomas Huth]

Am Fri, 20 Dec 2019 18:24:15 +0100
schrieb Laurent Vivier <address@hidden>:

> This is used by netBSD (and MacOS ROM) to detect the MMU type
> 
> Signed-off-by: Laurent Vivier <address@hidden>
> ---
> 
> Notes:
>     v2: change accordingly to Thomas' comments
>       - Replace MMU feature id by a CPU feature id
>       - fix 68030 mask
>       - add 68060 mask
>       - only mask in m68k_movec_to() function
> 
>  target/m68k/cpu.c    | 27 +++++++++++++++++++++------
>  target/m68k/cpu.h    |  5 ++++-
>  target/m68k/helper.c | 10 +++++++++-
>  3 files changed, 34 insertions(+), 8 deletions(-)
> 
> diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
> index e6596de29c..f6a46bf2fb 100644
> --- a/target/m68k/cpu.c
> +++ b/target/m68k/cpu.c
> @@ -114,11 +114,8 @@ static void m68000_cpu_initfn(Object *obj)
>      m68k_set_feature(env, M68K_FEATURE_MOVEP);
>  }
>  
> -static void m68020_cpu_initfn(Object *obj)
> +static void m680x0_cpu_common(CPUM68KState *env)

Maybe add a comment in front of the function that this is for 68020 -
68040, so that it is clear that it is not used for 68000 and 68060 ?

>  {
> -    M68kCPU *cpu = M68K_CPU(obj);
> -    CPUM68KState *env = &cpu->env;
> -
>      m68k_set_feature(env, M68K_FEATURE_M68000);

In the long run, we should maybe rename that flag to M68K_FEATURE_M680X0
or M68K_FEATURE_M68K to be able to distinguish between plain 68000 and
generic 680x0 features ... but let's do that in a later patch...

>      m68k_set_feature(env, M68K_FEATURE_USP);
>      m68k_set_feature(env, M68K_FEATURE_WORD_INDEX);
> @@ -136,14 +133,31 @@ static void m68020_cpu_initfn(Object *obj)
>      m68k_set_feature(env, M68K_FEATURE_CHK2);
>      m68k_set_feature(env, M68K_FEATURE_MOVEP);
>  }
> -#define m68030_cpu_initfn m68020_cpu_initfn
> +
> +static void m68020_cpu_initfn(Object *obj)
> +{
> +    M68kCPU *cpu = M68K_CPU(obj);
> +    CPUM68KState *env = &cpu->env;
> +
> +    m680x0_cpu_common(env);
> +    m68k_set_feature(env, M68K_FEATURE_M68020);
> +}
> +
> +static void m68030_cpu_initfn(Object *obj)
> +{
> +    M68kCPU *cpu = M68K_CPU(obj);
> +    CPUM68KState *env = &cpu->env;
> +
> +    m680x0_cpu_common(env);
> +    m68k_set_feature(env, M68K_FEATURE_M68030);
> +}
>  
>  static void m68040_cpu_initfn(Object *obj)
>  {
>      M68kCPU *cpu = M68K_CPU(obj);
>      CPUM68KState *env = &cpu->env;
>  
> -    m68020_cpu_initfn(obj);
> +    m680x0_cpu_common(env);
>      m68k_set_feature(env, M68K_FEATURE_M68040);
>  }
>  
> @@ -166,6 +180,7 @@ static void m68060_cpu_initfn(Object *obj)
>      m68k_set_feature(env, M68K_FEATURE_BKPT);
>      m68k_set_feature(env, M68K_FEATURE_RTD);
>      m68k_set_feature(env, M68K_FEATURE_CHK2);
> +    m68k_set_feature(env, M68K_FEATURE_M68060);
>  }
>  
>  static void m5208_cpu_initfn(Object *obj)
> diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
> index 20de3c379a..11c71fa962 100644
> --- a/target/m68k/cpu.h
> +++ b/target/m68k/cpu.h
> @@ -460,6 +460,10 @@ void do_m68k_semihosting(CPUM68KState *env, int
> nr); 
>  enum m68k_features {
>      M68K_FEATURE_M68000,
> +    M68K_FEATURE_M68020,
> +    M68K_FEATURE_M68030,
> +    M68K_FEATURE_M68040,
> +    M68K_FEATURE_M68060,
>      M68K_FEATURE_CF_ISA_A,
>      M68K_FEATURE_CF_ISA_B, /* (ISA B or C).  */
>      M68K_FEATURE_CF_ISA_APLUSC, /* BIT/BITREV, FF1, STRLDSR (ISA A+
> or C).  */ @@ -481,7 +485,6 @@ enum m68k_features {
>      M68K_FEATURE_BKPT,
>      M68K_FEATURE_RTD,
>      M68K_FEATURE_CHK2,
> -    M68K_FEATURE_M68040, /* instructions specific to MC68040 */
>      M68K_FEATURE_MOVEP,
>  };
>  
> diff --git a/target/m68k/helper.c b/target/m68k/helper.c
> index ae766a6cb0..4aa13b34ed 100644
> --- a/target/m68k/helper.c
> +++ b/target/m68k/helper.c
> @@ -205,7 +205,15 @@ void HELPER(m68k_movec_to)(CPUM68KState *env,
> uint32_t reg, uint32_t val) return;
>      /* MC680[234]0 */
>      case M68K_CR_CACR:
> -        env->cacr = val;
> +        if (m68k_feature(env, M68K_FEATURE_M68020)) {
> +            env->cacr = val & 0x0000000f;
> +        } else if (m68k_feature(env, M68K_FEATURE_M68030)) {
> +            env->cacr = val & 0x00003f1f;
> +        } else if (m68k_feature(env, M68K_FEATURE_M68040)) {
> +            env->cacr = val & 0x80008000;
> +        } else if (m68k_feature(env, M68K_FEATURE_M68060)) {
> +            env->cacr = val & 0xf8e0e000;
> +        }
>          m68k_switch_sp(env);
>          return;
>      /* MC680[34]0 */

Reviewed-by: Thomas Huth <address@hidden>