Re: [PATCH 04/18] target: Declare FOO_CPU_TYPE_NAME/SUFFIX in 'cpu-qom.h'

[Philippe Mathieu-Daudé]

Hi Zhiwei,

On 11/10/23 04:51, LIU Zhiwei wrote:
> On 2023/10/10 17:28, Philippe Mathieu-Daudé wrote:
> > Hegerogeneous code needs access to the FOO_CPU_TYPE_NAME()
> > macro to resolve target CPU types.
>
> Hi Philippe,
>
> I don't understand why should we use FOO_CPU_TYPE_NAME macro to resolve 
> target CPU types? In my opinion, we should pass the
> CPU typename from command line for heterogeneous case.
>
> Could you make it clearer how should we use FOO_CPU_TYPE_NAME macro to 
> resolve target CPU types in heterogeneous case?

To be honest I start to feel a bit lost with the "cpu
resolving type" design.

We are not quite there yet to "create from command line"
or "create from QMP", so I'm prototyping in plain C.
One of my test is:

  #include "target/arm/cpu-qom.h"
  #include "target/hexagon/cpu-qom.h"
  ...

  static void
  my_machine3_init((MachineState *machine)
  {
    CPUState cpu[2];
    ...

    cpu[0] = CPU(object_new(ARM_CPU_TYPE_NAME("cortex-a72")));
    cpu[1] = CPU(object_new(HEXAGON_CPU_TYPE_NAME("v68")));
    ...
  }

The machine code need access to the per-target
FOO_CPU_TYPE_NAME() macros. I'm not sure what each macro
expands to is considered stable, so IIUC I can't inline and use:

    cpu[0] = CPU(object_new("cortex-a72-arm-cpu"));
    cpu[1] = CPU(object_new("v68"-hexagon-cpu));

That said, maybe I'm mistaken.

Kinda related discussion with Gavin/Igor:
https://lore.kernel.org/qemu-devel/35653f53-a977-02ea-28f6-6fe85b1efd5a@redhat.com/
(related to 
https://lore.kernel.org/qemu-devel/20230907003553.1636896-1-gshan@redhat.com/).

> Thanks,
> Zhiwei
>
> > Move the declaration
> > (along with the required FOO_CPU_TYPE_SUFFIX) to "cpu-qom.h".
> >
> > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > ---
> >   target/alpha/cpu-qom.h   | 5 ++++-
> >   target/alpha/cpu.h       | 2 --
> >   target/avr/cpu-qom.h     | 5 ++++-
> >   target/avr/cpu.h         | 2 --
> >   target/cris/cpu-qom.h    | 5 ++++-
> >   target/cris/cpu.h        | 2 --
> >   target/i386/cpu-qom.h    | 3 +++
> >   target/i386/cpu.h        | 2 --
> >   target/m68k/cpu-qom.h    | 5 ++++-
> >   target/m68k/cpu.h        | 2 --
> >   target/mips/cpu-qom.h    | 3 +++
> >   target/mips/cpu.h        | 2 --
> >   target/rx/cpu-qom.h      | 5 ++++-
> >   target/rx/cpu.h          | 2 --
> >   target/s390x/cpu-qom.h   | 5 ++++-
> >   target/s390x/cpu.h       | 2 --
> >   target/sh4/cpu-qom.h     | 5 ++++-
> >   target/sh4/cpu.h         | 2 --
> >   target/sparc/cpu-qom.h   | 5 ++++-
> >   target/sparc/cpu.h       | 2 --
> >   target/tricore/cpu-qom.h | 5 +++++
> >   target/tricore/cpu.h     | 2 --
> >   target/xtensa/cpu-qom.h  | 5 ++++-
> >   target/xtensa/cpu.h      | 2 --
> >   24 files changed, 47 insertions(+), 33 deletions(-)
> >
> > diff --git a/target/alpha/cpu-qom.h b/target/alpha/cpu-qom.h
> > index 1f200724b6..d596d1b69f 100644
> > --- a/target/alpha/cpu-qom.h
> > +++ b/target/alpha/cpu-qom.h
> > @@ -1,5 +1,5 @@
> >   /*
> > - * QEMU Alpha CPU
> > + * QEMU Alpha CPU QOM header (target agnostic)
> >    *
> >    * Copyright (c) 2012 SUSE LINUX Products GmbH
> >    *
> > @@ -27,6 +27,9 @@
> >   OBJECT_DECLARE_CPU_TYPE(AlphaCPU, AlphaCPUClass, ALPHA_CPU)
> > +#define ALPHA_CPU_TYPE_SUFFIX "-" TYPE_ALPHA_CPU
> > +#define ALPHA_CPU_TYPE_NAME(model) model ALPHA_CPU_TYPE_SUFFIX
> > +
> >   /**
> >    * AlphaCPUClass:
> >    * @parent_realize: The parent class' realize handler.
> > diff --git a/target/alpha/cpu.h b/target/alpha/cpu.h
> > index e2a467ec17..ba0d9e3468 100644
> > --- a/target/alpha/cpu.h
> > +++ b/target/alpha/cpu.h
> > @@ -428,8 +428,6 @@ enum {
> >   void alpha_translate_init(void);
> > -#define ALPHA_CPU_TYPE_SUFFIX "-" TYPE_ALPHA_CPU
> > -#define ALPHA_CPU_TYPE_NAME(model) model ALPHA_CPU_TYPE_SUFFIX
> >   #define CPU_RESOLVING_TYPE TYPE_ALPHA_CPU
> >   void alpha_cpu_list(void);
[...]