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

[Philippe Mathieu-Daudé]

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.