Re: [Qemu-devel] [PATCH 14/28] m68k: replace cpu_m68k_init() with cpu_generic_init()

[Laurent Vivier]

Le 14/08/2017 à 10:00, Igor Mammedov a écrit :
> On Mon, 17 Jul 2017 17:23:22 +0200
> Igor Mammedov <address@hidden> wrote:
> 
>> On Mon, 17 Jul 2017 17:05:15 +0200
>> Andreas Färber <address@hidden> wrote:
>>
>>> Am 17.07.2017 um 12:41 schrieb Igor Mammedov:  
>>>> On Sat, 15 Jul 2017 08:08:58 -1000
>>>> Richard Henderson <address@hidden> wrote:
>>>>     
>>>>> On 07/14/2017 03:52 AM, Igor Mammedov wrote:    
>>>>>> @@ -230,6 +230,8 @@ static void m68k_cpu_realizefn(DeviceState *dev, 
>>>>>> Error **errp)
>>>>>>       M68kCPUClass *mcc = M68K_CPU_GET_CLASS(dev);
>>>>>>       Error *local_err = NULL;
>>>>>>   
>>>>>> +    register_m68k_insns(&cpu->env);
>>>>>> +      
>>>>>
>>>>> I think it would make more sense to do this during m68k_tcg_init.
>>>>>    
>>>> it seems that m68k_cpu_initfn accesses 'env' via some global,
>>>> while cpu_mk68k_init() used to access concrete pointer of just created cpu,
>>>>
>>>> how about moving register_m68k_insns() to m68k_cpu_initfn(), instead?
>>>> it should be equivalent to what cpu_mk68k_init() used to do.    
>>>
>>> As a general note, realize should be re-entrant. Can't tell from the
>>> above diff whether that is the case here.  
>> Looking at
>>
>> void register_m68k_insns (CPUM68KState *env)                                 
>>     
>> {                                                                            
>>     
>>     /* Build the opcode table only once to avoid                             
>>     
>>        multithreading issues. */                                             
>>     
>>     if (opcode_table[0] != NULL) {                                           
>>     
>>         return;                                                              
>>     
>>     }
>>
>> it is save to use multiple times,
>>
>> also looking further in it:
>>
>> #define BASE(name, opcode, mask) \                                           
>>     
>>     register_opcode(disas_##name, 0x##opcode, 0x##mask)                      
>>     
>> #define INSN(name, opcode, mask, feature) do { \                             
>>     
>>     if (m68k_feature(env, M68K_FEATURE_##feature)) \                         
>>     
>>         BASE(name, opcode, mask); \                                          
>>     
>>     } while(0)                                                               
>>     
>>     BASE(undef,     0000, 0000);                                             
>>     
>>     INSN(arith_im,  0080, fff8, CF_ISA_A);
>>
>> INSN macro depends on enabled features, it might work with current code that
>> has no user settable features but it will break once that is available.
>>
>> So I retract my suggestion to move register_m68k_insns() into 
>> m68k_cpu_initfn()
>> and keep it as it's in this patch (in m68k_cpu_realizefn()),
>> that way features theoretically set between initfn(and m68k_tcg_init) and 
>> realize() will
>> have effect on created cpu and we won't have to fix it in future.
> 
> Richard, Laurent,
> 
> Do you agree with keeping register_m68k_insns() in realize()?
> 

I agree.

Acked-by: Laurent Vivier <address@hidden>