[PATCH] hw/ppc: Deprecate the ref405ep and taihu machines and the 405 CPU models

[PATCH] hw/ppc: Deprecate the ref405ep and taihu machines and the 405 CPU models

[Thomas Huth]

These machines need a firmware image called 'ppc405_rom.bin', and nobody
seems to have such a firmware image left for testing, so the machines are
currently unusable. There used to be support in U-Boot, but it has been
removed a couple of year ago already.
Thus let's mark these boards and the 405 CPU as deprecated now, so that we
could remove them in a couple of releases (unless somebody speaks up and
says that these are still usefull for them).

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 docs/about/deprecated.rst | 15 +++++++++++++++
 hw/ppc/ppc405_boards.c    |  2 ++
 2 files changed, 17 insertions(+)

diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index 2f7db9a98d..27c03ef624 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -238,6 +238,11 @@ The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
 (the ISA has never been upstreamed to a compiler toolchain). Therefore
 this CPU is also deprecated.
 
+PPC 405 CPU models (since 6.2)
+''''''''''''''''''''''''''''''
+
+The related boards ``ref405ep`` and ``taihu`` are marked as deprecated, too.
+
 
 QEMU API (QAPI) events
 ----------------------
@@ -258,6 +263,16 @@ This machine is deprecated because we have enough AST2500 based OpenPOWER
 machines. It can be easily replaced by the ``witherspoon-bmc`` or the
 ``romulus-bmc`` machines.
 
+``ref405ep`` and ``taihu`` machines (since 6.2)
+'''''''''''''''''''''''''''''''''''''''''''''''
+
+These machines need a firmware image called 'ppc405_rom.bin', and nobody seems
+to have a working copy of such a firmware image anymore. `Support in U-Boot
+<https://gitlab.com/qemu-project/u-boot/-/commit/98f705c9cefdfdba62c069>`__
+has been removed a couple of years ago, too, so it is very unlikely that
+anybody is still using this code at all.
+
+
 Backend options
 ---------------
 
diff --git a/hw/ppc/ppc405_boards.c b/hw/ppc/ppc405_boards.c
index 972a7a4a3e..1578c0dac8 100644
--- a/hw/ppc/ppc405_boards.c
+++ b/hw/ppc/ppc405_boards.c
@@ -317,6 +317,7 @@ static void ref405ep_class_init(ObjectClass *oc, void *data)
     mc->init = ref405ep_init;
     mc->default_ram_size = 0x08000000;
     mc->default_ram_id = "ef405ep.ram";
+    mc->deprecation_reason = "ppc405 CPU is deprecated";
 }
 
 static const TypeInfo ref405ep_type = {
@@ -547,6 +548,7 @@ static void taihu_class_init(ObjectClass *oc, void *data)
     mc->init = taihu_405ep_init;
     mc->default_ram_size = 0x08000000;
     mc->default_ram_id = "taihu_405ep.ram";
+    mc->deprecation_reason = "ppc405 CPU is deprecated";
 }
 
 static const TypeInfo taihu_type = {
-- 
2.27.0

Re: [PATCH] hw/ppc: Deprecate the ref405ep and taihu machines and the 405 CPU models

[Cédric Le Goater]

On 10/1/21 14:19, Thomas Huth wrote:
> These machines need a firmware image called 'ppc405_rom.bin', and nobody
> seems to have such a firmware image left for testing, so the machines are
> currently unusable. There used to be support in U-Boot, but it has been
> removed a couple of year ago already.
> Thus let's mark these boards and the 405 CPU as deprecated now, so that we
> could remove them in a couple of releases (unless somebody speaks up and
> says that these are still usefull for them).
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Reviewed-by: Cédric Le Goater <clg@kaod.org>


> ---
>   docs/about/deprecated.rst | 15 +++++++++++++++
>   hw/ppc/ppc405_boards.c    |  2 ++
>   2 files changed, 17 insertions(+)
> 
> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
> index 2f7db9a98d..27c03ef624 100644
> --- a/docs/about/deprecated.rst
> +++ b/docs/about/deprecated.rst
> @@ -238,6 +238,11 @@ The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
>   (the ISA has never been upstreamed to a compiler toolchain). Therefore
>   this CPU is also deprecated.
>   
> +PPC 405 CPU models (since 6.2)
> +''''''''''''''''''''''''''''''
> +
> +The related boards ``ref405ep`` and ``taihu`` are marked as deprecated, too.
> +
>   
>   QEMU API (QAPI) events
>   ----------------------
> @@ -258,6 +263,16 @@ This machine is deprecated because we have enough AST2500 based OpenPOWER
>   machines. It can be easily replaced by the ``witherspoon-bmc`` or the
>   ``romulus-bmc`` machines.
>   
> +``ref405ep`` and ``taihu`` machines (since 6.2)
> +'''''''''''''''''''''''''''''''''''''''''''''''
> +
> +These machines need a firmware image called 'ppc405_rom.bin', and nobody seems
> +to have a working copy of such a firmware image anymore. `Support in U-Boot
> +<https://gitlab.com/qemu-project/u-boot/-/commit/98f705c9cefdfdba62c069>`__
> +has been removed a couple of years ago, too, so it is very unlikely that
> +anybody is still using this code at all.
> +
> +
>   Backend options
>   ---------------
>   
> diff --git a/hw/ppc/ppc405_boards.c b/hw/ppc/ppc405_boards.c
> index 972a7a4a3e..1578c0dac8 100644
> --- a/hw/ppc/ppc405_boards.c
> +++ b/hw/ppc/ppc405_boards.c
> @@ -317,6 +317,7 @@ static void ref405ep_class_init(ObjectClass *oc, void *data)
>       mc->init = ref405ep_init;
>       mc->default_ram_size = 0x08000000;
>       mc->default_ram_id = "ef405ep.ram";
> +    mc->deprecation_reason = "ppc405 CPU is deprecated";
>   }
>   
>   static const TypeInfo ref405ep_type = {
> @@ -547,6 +548,7 @@ static void taihu_class_init(ObjectClass *oc, void *data)
>       mc->init = taihu_405ep_init;
>       mc->default_ram_size = 0x08000000;
>       mc->default_ram_id = "taihu_405ep.ram";
> +    mc->deprecation_reason = "ppc405 CPU is deprecated";
>   }
>   
>   static const TypeInfo taihu_type = {
> 

Re: [PATCH] hw/ppc: Deprecate the ref405ep and taihu machines and the 405 CPU models

[Peter Maydell]

On Fri, 1 Oct 2021 at 13:22, Thomas Huth <thuth@redhat.com> wrote:
>
> These machines need a firmware image called 'ppc405_rom.bin', and nobody
> seems to have such a firmware image left for testing, so the machines are
> currently unusable. There used to be support in U-Boot, but it has been
> removed a couple of year ago already.
> Thus let's mark these boards and the 405 CPU as deprecated now, so that we
> could remove them in a couple of releases (unless somebody speaks up and
> says that these are still usefull for them).
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  docs/about/deprecated.rst | 15 +++++++++++++++
>  hw/ppc/ppc405_boards.c    |  2 ++
>  2 files changed, 17 insertions(+)
>
> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
> index 2f7db9a98d..27c03ef624 100644
> --- a/docs/about/deprecated.rst
> +++ b/docs/about/deprecated.rst
> @@ -238,6 +238,11 @@ The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
>  (the ISA has never been upstreamed to a compiler toolchain). Therefore
>  this CPU is also deprecated.
>
> +PPC 405 CPU models (since 6.2)
> +''''''''''''''''''''''''''''''
> +
> +The related boards ``ref405ep`` and ``taihu`` are marked as deprecated, too.
> +

What is this "too" a reference to? The immediately preceding section
in the document is about the MIPS I7200 CPU model.

The not-being-deprecated sam460ex board also uses the ppc405 CPU
I think, so I don't think we can drop the CPU models.

>  QEMU API (QAPI) events
>  ----------------------
> @@ -258,6 +263,16 @@ This machine is deprecated because we have enough AST2500 based OpenPOWER
>  machines. It can be easily replaced by the ``witherspoon-bmc`` or the
>  ``romulus-bmc`` machines.
>
> +``ref405ep`` and ``taihu`` machines (since 6.2)
> +'''''''''''''''''''''''''''''''''''''''''''''''
> +
> +These machines need a firmware image called 'ppc405_rom.bin', and nobody seems
> +to have a working copy of such a firmware image anymore. `Support in U-Boot

"any more".

> +<https://gitlab.com/qemu-project/u-boot/-/commit/98f705c9cefdfdba62c069>`__
> +has been removed a couple of years ago, too, so it is very unlikely that
> +anybody is still using this code at all.

(I'm not sure whether anybody ever actually successfully booted a
u-boot binary on QEMU's taihu/ref405ep boards.)

> +
> +
>  Backend options
>  ---------------
>
> diff --git a/hw/ppc/ppc405_boards.c b/hw/ppc/ppc405_boards.c
> index 972a7a4a3e..1578c0dac8 100644
> --- a/hw/ppc/ppc405_boards.c
> +++ b/hw/ppc/ppc405_boards.c
> @@ -317,6 +317,7 @@ static void ref405ep_class_init(ObjectClass *oc, void *data)
>      mc->init = ref405ep_init;
>      mc->default_ram_size = 0x08000000;
>      mc->default_ram_id = "ef405ep.ram";
> +    mc->deprecation_reason = "ppc405 CPU is deprecated";
>  }
>
>  static const TypeInfo ref405ep_type = {
> @@ -547,6 +548,7 @@ static void taihu_class_init(ObjectClass *oc, void *data)
>      mc->init = taihu_405ep_init;
>      mc->default_ram_size = 0x08000000;
>      mc->default_ram_id = "taihu_405ep.ram";
> +    mc->deprecation_reason = "ppc405 CPU is deprecated";
>  }

We're not deprecating the machine types because we're deprecating
the CPU types. We're deprecating them because we believe that
nobody's using them.

-- PMM

Re: [PATCH] hw/ppc: Deprecate the ref405ep and taihu machines and the 405 CPU models

[Philippe Mathieu-Daudé]

On 10/1/21 14:46, Peter Maydell wrote:
> On Fri, 1 Oct 2021 at 13:22, Thomas Huth <thuth@redhat.com> wrote:

>> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
>> index 2f7db9a98d..27c03ef624 100644
>> --- a/docs/about/deprecated.rst
>> +++ b/docs/about/deprecated.rst
>> @@ -238,6 +238,11 @@ The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
>>  (the ISA has never been upstreamed to a compiler toolchain). Therefore
>>  this CPU is also deprecated.
>>
>> +PPC 405 CPU models (since 6.2)
>> +''''''''''''''''''''''''''''''
>> +
>> +The related boards ``ref405ep`` and ``taihu`` are marked as deprecated, too.
>> +
> 
> What is this "too" a reference to? The immediately preceding section
> in the document is about the MIPS I7200 CPU model.
> 
> The not-being-deprecated sam460ex board also uses the ppc405 CPU
> I think, so I don't think we can drop the CPU models.

>> +    mc->deprecation_reason = "ppc405 CPU is deprecated";
>>  }
> 
> We're not deprecating the machine types because we're deprecating
> the CPU types. We're deprecating them because we believe that
> nobody's using them.

OTOH we mostly test default CPUs. I am a bit worried about CPU
coverage in general. I'm not suggesting we should remove old
CPUs along with their machines, because we can still test an ISA,
just worried about having so many code paths uncovered.

Re: [PATCH] hw/ppc: Deprecate the ref405ep and taihu machines and the 405 CPU models

[Thomas Huth]

On 01/10/2021 14.46, Peter Maydell wrote:
> On Fri, 1 Oct 2021 at 13:22, Thomas Huth <thuth@redhat.com> wrote:
>>
>> These machines need a firmware image called 'ppc405_rom.bin', and nobody
>> seems to have such a firmware image left for testing, so the machines are
>> currently unusable. There used to be support in U-Boot, but it has been
>> removed a couple of year ago already.
>> Thus let's mark these boards and the 405 CPU as deprecated now, so that we
>> could remove them in a couple of releases (unless somebody speaks up and
>> says that these are still usefull for them).
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   docs/about/deprecated.rst | 15 +++++++++++++++
>>   hw/ppc/ppc405_boards.c    |  2 ++
>>   2 files changed, 17 insertions(+)
>>
>> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
>> index 2f7db9a98d..27c03ef624 100644
>> --- a/docs/about/deprecated.rst
>> +++ b/docs/about/deprecated.rst
>> @@ -238,6 +238,11 @@ The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
>>   (the ISA has never been upstreamed to a compiler toolchain). Therefore
>>   this CPU is also deprecated.
>>
>> +PPC 405 CPU models (since 6.2)
>> +''''''''''''''''''''''''''''''
>> +
>> +The related boards ``ref405ep`` and ``taihu`` are marked as deprecated, too.
>> +
> 
> What is this "too" a reference to? The immediately preceding section
> in the document is about the MIPS I7200 CPU model.

It was meant as a reference to the machines below. I'll try to rephrase in v2.
(As far as I can see, the 405 can only be used on these boards, it does not 
seem to be possible to use these CPU types on other boards)

> The not-being-deprecated sam460ex board also uses the ppc405 CPU
> I think, so I don't think we can drop the CPU models.

No, that board uses a 460exb CPU which is a slightly different kind of 
embedded PPC CPU, as far as I know.

>>   QEMU API (QAPI) events
>>   ----------------------
>> @@ -258,6 +263,16 @@ This machine is deprecated because we have enough AST2500 based OpenPOWER
>>   machines. It can be easily replaced by the ``witherspoon-bmc`` or the
>>   ``romulus-bmc`` machines.
>>
>> +``ref405ep`` and ``taihu`` machines (since 6.2)
>> +'''''''''''''''''''''''''''''''''''''''''''''''
>> +
>> +These machines need a firmware image called 'ppc405_rom.bin', and nobody seems
>> +to have a working copy of such a firmware image anymore. `Support in U-Boot
> 
> "any more".
> 
>> +<https://gitlab.com/qemu-project/u-boot/-/commit/98f705c9cefdfdba62c069>`__
>> +has been removed a couple of years ago, too, so it is very unlikely that
>> +anybody is still using this code at all.
> 
> (I'm not sure whether anybody ever actually successfully booted a
> u-boot binary on QEMU's taihu/ref405ep boards.)

Me neither. Maybe I should rather drop that reference in v2...
but I still wonder where that "ppc405_rom.bin" originally came from...

>>   Backend options
>>   ---------------
>>
>> diff --git a/hw/ppc/ppc405_boards.c b/hw/ppc/ppc405_boards.c
>> index 972a7a4a3e..1578c0dac8 100644
>> --- a/hw/ppc/ppc405_boards.c
>> +++ b/hw/ppc/ppc405_boards.c
>> @@ -317,6 +317,7 @@ static void ref405ep_class_init(ObjectClass *oc, void *data)
>>       mc->init = ref405ep_init;
>>       mc->default_ram_size = 0x08000000;
>>       mc->default_ram_id = "ef405ep.ram";
>> +    mc->deprecation_reason = "ppc405 CPU is deprecated";
>>   }
>>
>>   static const TypeInfo ref405ep_type = {
>> @@ -547,6 +548,7 @@ static void taihu_class_init(ObjectClass *oc, void *data)
>>       mc->init = taihu_405ep_init;
>>       mc->default_ram_size = 0x08000000;
>>       mc->default_ram_id = "taihu_405ep.ram";
>> +    mc->deprecation_reason = "ppc405 CPU is deprecated";
>>   }
> 
> We're not deprecating the machine types because we're deprecating
> the CPU types. We're deprecating them because we believe that
> nobody's using them.

Ok, I'll try to come up with a different text instead.

  Thomas

Re: [PATCH] hw/ppc: Deprecate the ref405ep and taihu machines and the 405 CPU models

[Daniel P. Berrangé]

On Fri, Oct 01, 2021 at 03:01:08PM +0200, Thomas Huth wrote:
> On 01/10/2021 14.46, Peter Maydell wrote:
> > On Fri, 1 Oct 2021 at 13:22, Thomas Huth <thuth@redhat.com> wrote:
> > > 
> > > These machines need a firmware image called 'ppc405_rom.bin', and nobody
> > > seems to have such a firmware image left for testing, so the machines are
> > > currently unusable. There used to be support in U-Boot, but it has been
> > > removed a couple of year ago already.
> > > Thus let's mark these boards and the 405 CPU as deprecated now, so that we
> > > could remove them in a couple of releases (unless somebody speaks up and
> > > says that these are still usefull for them).
> > > 
> > > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > > ---
> > >   docs/about/deprecated.rst | 15 +++++++++++++++
> > >   hw/ppc/ppc405_boards.c    |  2 ++
> > >   2 files changed, 17 insertions(+)
> > > 
> > > diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
> > > index 2f7db9a98d..27c03ef624 100644
> > > --- a/docs/about/deprecated.rst
> > > +++ b/docs/about/deprecated.rst
> > > @@ -238,6 +238,11 @@ The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
> > >   (the ISA has never been upstreamed to a compiler toolchain). Therefore
> > >   this CPU is also deprecated.
> > > 
> > > +PPC 405 CPU models (since 6.2)
> > > +''''''''''''''''''''''''''''''
> > > +
> > > +The related boards ``ref405ep`` and ``taihu`` are marked as deprecated, too.
> > > +
> > 
> > What is this "too" a reference to? The immediately preceding section
> > in the document is about the MIPS I7200 CPU model.
> 
> It was meant as a reference to the machines below. I'll try to rephrase in v2.
> (As far as I can see, the 405 can only be used on these boards, it does not
> seem to be possible to use these CPU types on other boards)
> 
> > The not-being-deprecated sam460ex board also uses the ppc405 CPU
> > I think, so I don't think we can drop the CPU models.
> 
> No, that board uses a 460exb CPU which is a slightly different kind of
> embedded PPC CPU, as far as I know.
> 
> > >   QEMU API (QAPI) events
> > >   ----------------------
> > > @@ -258,6 +263,16 @@ This machine is deprecated because we have enough AST2500 based OpenPOWER
> > >   machines. It can be easily replaced by the ``witherspoon-bmc`` or the
> > >   ``romulus-bmc`` machines.
> > > 
> > > +``ref405ep`` and ``taihu`` machines (since 6.2)
> > > +'''''''''''''''''''''''''''''''''''''''''''''''
> > > +
> > > +These machines need a firmware image called 'ppc405_rom.bin', and nobody seems
> > > +to have a working copy of such a firmware image anymore. `Support in U-Boot
> > 
> > "any more".
> > 
> > > +<https://gitlab.com/qemu-project/u-boot/-/commit/98f705c9cefdfdba62c069>`__
> > > +has been removed a couple of years ago, too, so it is very unlikely that
> > > +anybody is still using this code at all.
> > 
> > (I'm not sure whether anybody ever actually successfully booted a
> > u-boot binary on QEMU's taihu/ref405ep boards.)
> 
> Me neither. Maybe I should rather drop that reference in v2...
> but I still wonder where that "ppc405_rom.bin" originally came from...
> 
> > >   Backend options
> > >   ---------------
> > > 
> > > diff --git a/hw/ppc/ppc405_boards.c b/hw/ppc/ppc405_boards.c
> > > index 972a7a4a3e..1578c0dac8 100644
> > > --- a/hw/ppc/ppc405_boards.c
> > > +++ b/hw/ppc/ppc405_boards.c
> > > @@ -317,6 +317,7 @@ static void ref405ep_class_init(ObjectClass *oc, void *data)
> > >       mc->init = ref405ep_init;
> > >       mc->default_ram_size = 0x08000000;
> > >       mc->default_ram_id = "ef405ep.ram";
> > > +    mc->deprecation_reason = "ppc405 CPU is deprecated";
> > >   }
> > > 
> > >   static const TypeInfo ref405ep_type = {
> > > @@ -547,6 +548,7 @@ static void taihu_class_init(ObjectClass *oc, void *data)
> > >       mc->init = taihu_405ep_init;
> > >       mc->default_ram_size = 0x08000000;
> > >       mc->default_ram_id = "taihu_405ep.ram";
> > > +    mc->deprecation_reason = "ppc405 CPU is deprecated";
> > >   }
> > 
> > We're not deprecating the machine types because we're deprecating
> > the CPU types. We're deprecating them because we believe that
> > nobody's using them.
> 
> Ok, I'll try to come up with a different text instead.

IIUC, the user isn't specifying the CPU on the command line, they
are specifying the machine type, and getting the fixed CPU model
as a side effect. With that in mind it is probably clearer to talk
about the machine type in the deprecation message as that corresponds
to their CLI args.

IOW   "machine taihu is deprecated"


Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|

Re: [PATCH] hw/ppc: Deprecate the ref405ep and taihu machines and the 405 CPU models

[Peter Maydell]

On Fri, 1 Oct 2021 at 14:01, Thomas Huth <thuth@redhat.com> wrote:
>
> On 01/10/2021 14.46, Peter Maydell wrote:
> > On Fri, 1 Oct 2021 at 13:22, Thomas Huth <thuth@redhat.com> wrote:
> >>
> >> These machines need a firmware image called 'ppc405_rom.bin', and nobody
> >> seems to have such a firmware image left for testing, so the machines are
> >> currently unusable. There used to be support in U-Boot, but it has been
> >> removed a couple of year ago already.
> >> Thus let's mark these boards and the 405 CPU as deprecated now, so that we
> >> could remove them in a couple of releases (unless somebody speaks up and
> >> says that these are still usefull for them).
> >>
> >> Signed-off-by: Thomas Huth <thuth@redhat.com>
> >> ---
> >>   docs/about/deprecated.rst | 15 +++++++++++++++
> >>   hw/ppc/ppc405_boards.c    |  2 ++
> >>   2 files changed, 17 insertions(+)
> >>
> >> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
> >> index 2f7db9a98d..27c03ef624 100644
> >> --- a/docs/about/deprecated.rst
> >> +++ b/docs/about/deprecated.rst
> >> @@ -238,6 +238,11 @@ The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
> >>   (the ISA has never been upstreamed to a compiler toolchain). Therefore
> >>   this CPU is also deprecated.
> >>
> >> +PPC 405 CPU models (since 6.2)
> >> +''''''''''''''''''''''''''''''
> >> +
> >> +The related boards ``ref405ep`` and ``taihu`` are marked as deprecated, too.
> >> +
> >
> > What is this "too" a reference to? The immediately preceding section
> > in the document is about the MIPS I7200 CPU model.
>
> It was meant as a reference to the machines below. I'll try to rephrase in v2.
> (As far as I can see, the 405 can only be used on these boards, it does not
> seem to be possible to use these CPU types on other boards)

OK. I think it's probably a good policy to make deprecation-notice
section text self-contained, because we're going to be regularly deleting
them, or moving them to removed-features.rst.

> > The not-being-deprecated sam460ex board also uses the ppc405 CPU
> > I think, so I don't think we can drop the CPU models.
>
> No, that board uses a 460exb CPU which is a slightly different kind of
> embedded PPC CPU, as far as I know.

Ah, right. I was confused because sam460ex.c calls ppc405_ebc_init(),
and so it came up from a quick grep for 'ppc405'.

If we want to deprecate the CPU models I think it would be useful
to list all the ones we're deprecating explicitly here (using the
names that the '-cpu' option accepts).

thanks
-- PMM

Re: [PATCH] hw/ppc: Deprecate the ref405ep and taihu machines and the 405 CPU models

[BALATON Zoltan]

On Fri, 1 Oct 2021, Peter Maydell wrote:
> On Fri, 1 Oct 2021 at 14:01, Thomas Huth <thuth@redhat.com> wrote:
>> On 01/10/2021 14.46, Peter Maydell wrote:
>>> On Fri, 1 Oct 2021 at 13:22, Thomas Huth <thuth@redhat.com> wrote:
>>>>
>>>> These machines need a firmware image called 'ppc405_rom.bin', and nobody
>>>> seems to have such a firmware image left for testing, so the machines are
>>>> currently unusable. There used to be support in U-Boot, but it has been
>>>> removed a couple of year ago already.
>>>> Thus let's mark these boards and the 405 CPU as deprecated now, so that we
>>>> could remove them in a couple of releases (unless somebody speaks up and
>>>> says that these are still usefull for them).
>>>>
>>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>>>> ---
>>>>   docs/about/deprecated.rst | 15 +++++++++++++++
>>>>   hw/ppc/ppc405_boards.c    |  2 ++
>>>>   2 files changed, 17 insertions(+)
>>>>
>>>> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
>>>> index 2f7db9a98d..27c03ef624 100644
>>>> --- a/docs/about/deprecated.rst
>>>> +++ b/docs/about/deprecated.rst
>>>> @@ -238,6 +238,11 @@ The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
>>>>   (the ISA has never been upstreamed to a compiler toolchain). Therefore
>>>>   this CPU is also deprecated.
>>>>
>>>> +PPC 405 CPU models (since 6.2)
>>>> +''''''''''''''''''''''''''''''
>>>> +
>>>> +The related boards ``ref405ep`` and ``taihu`` are marked as deprecated, too.
>>>> +
>>>
>>> What is this "too" a reference to? The immediately preceding section
>>> in the document is about the MIPS I7200 CPU model.
>>
>> It was meant as a reference to the machines below. I'll try to rephrase in v2.
>> (As far as I can see, the 405 can only be used on these boards, it does not
>> seem to be possible to use these CPU types on other boards)
>
> OK. I think it's probably a good policy to make deprecation-notice
> section text self-contained, because we're going to be regularly deleting
> them, or moving them to removed-features.rst.
>
>>> The not-being-deprecated sam460ex board also uses the ppc405 CPU
>>> I think, so I don't think we can drop the CPU models.
>>
>> No, that board uses a 460exb CPU which is a slightly different kind of
>> embedded PPC CPU, as far as I know.
>
> Ah, right. I was confused because sam460ex.c calls ppc405_ebc_init(),
> and so it came up from a quick grep for 'ppc405'.

The AMCC ppc460EX SoC the sam460ex is using has a PPC440 core but since 
these ppc4xx SoCs are based on previous ones they have similar parts which 
are reused. This was and still is quite a mess, I've tried to move some 
ppc440 specific parts to separate file and also common parts to ppc4xx 
when adding sam460ex but some parts from ppc405 is reused without moving 
it to ppc4xx and a lot of it is still predating QOM which would have been 
too much work to fix so left as it was before.

> If we want to deprecate the CPU models I think it would be useful
> to list all the ones we're deprecating explicitly here (using the
> names that the '-cpu' option accepts).

Maybe the ppc405 CPU should be kept due to the entaglement of ppc405 and 
ppc440 parts and also because it could be useful if somebody wants to try 
to run code for that CPU (with user mode or maybe qemi-system-ppc -M none 
-cpu ppc405 plus some other devices if needed).

Regards,
BALATON Zoltan