Re: [PATCH v2 3/8] machine: Print supported CPU models instead of typenames

[Gavin Shan <gshan@redhat.com>]

On 7/27/23 09:08, Richard Henderson wrote:
> On 7/25/23 17:32, Gavin Shan wrote:
>> -static const char *q800_machine_valid_cpu_types[] = {
>> +static const char * const q800_machine_valid_cpu_types[] = {
>>       M68K_CPU_TYPE_NAME("m68040"),
>>       NULL
>>   };
>> +static const char * const q800_machine_valid_cpu_models[] = {
>> +    "m68040",
>> +    NULL
>> +};
> 
> I really don't like this replication.
> 

Right, it's going to be lots of replications, but gives much flexibility.
There are 21 targets and we don't have fixed pattern for the mapping between
CPU model name and CPU typename. I'm summarizing the used patterns like below.

   1 All CPU model names are mappinged to fixed CPU typename;
   2 CPU model name is same to CPU typename;
   3 CPU model name is alias to CPU typename;
   4 CPU model name is prefix of CPU typename;

   Target         Categories    suffix-of-CPU-typename
   -------------------------------------------------------
   alpha          -234          -alpha-cpu
   arm            ---4          -arm-cpu
   avr            -2--
   cris           --34          -cris-cpu
   hexagon        ---4          -hexagon-cpu
   hppa           1---
   i386           ---4          -i386-cpu
   loongarch      -2-4          -loongarch-cpu
   m68k           ---4          -m68k-cpu
   microblaze     1---
   mips           ---4          -mips64-cpu  -mips-cpu
   nios2          1---
   openrisc       ---4          -or1k-cpu
   ppc            --34          -powerpc64-cpu  -powerpc-cpu
   riscv          ---4          -riscv-cpu
   rx             -2-4          -rx-cpu
   s390x          ---4          -s390x-cpu
   sh4            --34          -superh-cpu
   sparc          -2--
   tricore        ---4          -tricore-cpu
   xtensa         ---4          -xtensa-cpu

There are several options as below. Please let me know which one or something
else is the best.

(a) Keep what we have and use mc->valid_{cpu_types, cpu_models}[] to track
the valid CPU typenames and CPU model names.

(b) Introduce CPUClass::model_name_by_typename(). Every target has their own
implementation to convert CPU typename to CPU model name. The CPU model name
is parsed from mc->valid_cpu_types[i].

     char *CPUClass::model_by_typename(const char *typename);

(c) As we discussed before, use mc->valid_cpu_type_suffix and mc->valid_cpu_models
because the CPU type check is currently needed by target arm/m68k/riscv where we
do have fixed pattern to convert CPU model names to CPU typenames. The CPU typename
is comprised of CPU model name and suffix. However, it won't be working when the CPU
type check is required by other target where we have patterns other than this.

Thanks,
Gavin