Re: Deprecate the ppc405 boards in QEMU? (was: [PATCH v3 4/7] MAINTAINERS: Orphan obscure ppc platforms)

[Philippe Mathieu-Daudé]

+Richard

On 10/5/21 14:29, Thomas Huth wrote:
> On 05/10/2021 14.20, BALATON Zoltan wrote:
>> On Tue, 5 Oct 2021, Cédric Le Goater wrote:
>>> On 10/5/21 08:18, Alexey Kardashevskiy wrote:
>>>> On 05/10/2021 15:44, Christophe Leroy wrote:
>>>>> Le 05/10/2021 à 02:48, David Gibson a écrit :
>>>>>> On Fri, Oct 01, 2021 at 04:18:49PM +0200, Thomas Huth wrote:
>>>>>>> On 01/10/2021 15.04, Christophe Leroy wrote:
>>>>>>>> Le 01/10/2021 à 14:04, Thomas Huth a écrit :
>>>>>>>>> On 01/10/2021 13.12, Peter Maydell wrote:
>>>>>>>>>> On Fri, 1 Oct 2021 at 10:43, Thomas Huth <thuth@redhat.com>
>>>>>>>>>> wrote:
>>>>>>>>>>> Nevertheless, as long as nobody has a hint where to find that
>>>>>>>>>>> ppc405_rom.bin, I think both boards are pretty useless in
>>>>>>>>>>> QEMU (as far as I
>>>>>>>>>>> can see, they do not work without the bios at all, so it's
>>>>>>>>>>> also not possible
>>>>>>>>>>> to use a Linux image with the "-kernel" CLI option directly).
>>>>>>>>>>
>>>>>>>>>> It is at least in theory possible to run bare-metal code on
>>>>>>>>>> either board, by passing either a pflash or a bios argument.
>>>>>>>>>
>>>>>>>>> True. I did some more research, and seems like there was once
>>>>>>>>> support for those boards in u-boot, but it got removed there a
>>>>>>>>> couple of years ago already:
>>>>>>>>>
>>>>>>>>> https://gitlab.com/qemu-project/u-boot/-/commit/98f705c9cefdf
>>>>>>>>>
>>>>>>>>> https://gitlab.com/qemu-project/u-boot/-/commit/b147ff2f37d5b
>>>>>>>>>
>>>>>>>>> https://gitlab.com/qemu-project/u-boot/-/commit/7514037bcdc37
>>>>>>>>>
>>>>>>>>>> But I agree that there seem to be no signs of anybody actually
>>>>>>>>>> successfully using these boards for anything, so we should
>>>>>>>>>> deprecate-and-delete them.
>>>>>>>>>
>>>>>>>>> Yes, let's mark them as deprecated now ... if someone still uses
>>>>>>>>> them and speaks up, we can still revert the deprecation again.
>>>>>>>>
>>>>>>>> I really would like to be able to use them to validate Linux Kernel
>>>>>>>> changes, hence looking for that missing BIOS.
>>>>>>>>
>>>>>>>> If we remove ppc405 from QEMU, we won't be able to do any
>>>>>>>> regression
>>>>>>>> tests of Linux Kernel on those processors.
>>>>>>>
>>>>>>> If you/someone managed to compile an old version of u-boot for
>>>>>>> one of these
>>>>>>> two boards, so that we would finally have something for
>>>>>>> regression testing,
>>>>>>> we can of course also keep the boards in QEMU...
>>>>>>
>>>>>> I can see that it would be usefor for some cases, but unless someone
>>>>>> volunteers to track down the necessary firmware and look after it, I
>>>>>> think we do need to deprecate it - I certainly don't have the
>>>>>> capacity
>>>>>> to look into this.
>>>>>>
>>>>>
>>>>> I will look at it, please allow me a few weeks though.
>>>>
>>>> Well, building it was not hard but now I'd like to know what board
>>>> QEMU actually emulates, there are way too many codenames and PVRs.
>>>
>>> yes. We should try to reduce the list below. Deprecating embedded
>>> machines
>>> is one way.
>>
>> Why should we reduce that list? It's good to have different cpu
>> options when one wants to test code for different PPC versions (maybe
>> also in user mode) or just to have a quick list of these at one place.
> 
> I think there are many CPUs in that list which cannot be used with any
> board, some of them might be also in a very incomplete state. So
> presenting such a big list to the users is confusing and might create
> wrong expectations. It would be good to remove at least the CPUs which
> are really completely useless.

Maybe only remove some from system emulation but keep all of them
in user emulation?