Re: [PATCH 17/18] target/mips: Make MIPS_CPU common to new MIPS32_CPU / MIPS64_CPU types

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 13/10/23 06:34, Richard Henderson wrote:
> On 10/10/23 02:28, Philippe Mathieu-Daudé wrote:
>> "target/foo/cpu-qom.h" can not use any target specific definitions.
>>
>> Currently "target/mips/cpu-qom.h" defines TYPE_MIPS_CPU depending
>> on the mips(32)/mips64 build type. This doesn't scale in a
>> heterogeneous context where we need to access both types concurrently.
>>
>> In order to do that, introduce the new MIPS32_CPU / MIPS64_CPU types,
>> both inheriting a common TYPE_MIPS_CPU base type.
>>
>> Keep the current CPU types registered in mips_register_cpudef_type()
>> as 32 or 64-bit, but instead of depending on the binary built being
>> targeting 32/64-bit, check whether the CPU is 64-bit by looking at
>> the CPU_MIPS64 bit.
>>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>> ---
>>   target/mips/cpu-qom.h | 13 ++++++-------
>>   target/mips/cpu.h     |  3 +++
>>   target/mips/cpu.c     | 11 ++++++++++-
>>   3 files changed, 19 insertions(+), 8 deletions(-)
>>
>> diff --git a/target/mips/cpu-qom.h b/target/mips/cpu-qom.h
>> index 9c98ca1956..1a71509b5e 100644
>> --- a/target/mips/cpu-qom.h
>> +++ b/target/mips/cpu-qom.h
>> @@ -1,5 +1,5 @@
>>   /*
>> - * QEMU MIPS CPU
>> + * QEMU MIPS CPU QOM header (target agnostic)
>>    *
>>    * Copyright (c) 2012 SUSE LINUX Products GmbH
>>    *
>> @@ -23,13 +23,12 @@
>>   #include "hw/core/cpu.h"
>>   #include "qom/object.h"
>> -#ifdef TARGET_MIPS64
>> -#define TYPE_MIPS_CPU "mips64-cpu"
>> -#else
>> -#define TYPE_MIPS_CPU "mips-cpu"
>> -#endif
>> +#define TYPE_MIPS_CPU   "mips-cpu"
>> +#define TYPE_MIPS32_CPU "mips32-cpu"
>> +#define TYPE_MIPS64_CPU "mips64-cpu"
>> -OBJECT_DECLARE_CPU_TYPE(MIPSCPU, MIPSCPUClass, MIPS_CPU)
>> +OBJECT_DECLARE_CPU_TYPE(MIPS32CPU, MIPSCPUClass, MIPS32_CPU)
>> +OBJECT_DECLARE_CPU_TYPE(MIPS64CPU, MIPSCPUClass, MIPS64_CPU)
>>   #define MIPS_CPU_TYPE_SUFFIX "-" TYPE_MIPS_CPU
>>   #define MIPS_CPU_TYPE_NAME(model) model MIPS_CPU_TYPE_SUFFIX
>> diff --git a/target/mips/cpu.h b/target/mips/cpu.h
>> index 6b026e6bcf..3b6d0a7a8a 100644
>> --- a/target/mips/cpu.h
>> +++ b/target/mips/cpu.h
>> @@ -10,6 +10,9 @@
>>   #include "hw/clock.h"
>>   #include "mips-defs.h"
>> +/* Abstract QOM MIPS CPU, not exposed to other targets */
>> +OBJECT_DECLARE_CPU_TYPE(MIPSCPU, MIPSCPUClass, MIPS_CPU)
> 
> Why is this one moved back to cpu.h?
> You exposed TYPE_X86_CPU in i386/cpu-qom.h...

First thinking was to expose the base TYPE, so we can use QOM methods
to enumerate implementations, but not expose QOM state/class getter
for the base type (except in target/foo/). HW would use concrete
32 or 64b type state/class getter. I might be wrong, so I'll keep
the base type exposed for now. We might restrict later.