Re: [PATCH] hw/ppc/prep: Remove the deprecated "prep" machine and the OpenHackware BIOS

[Paolo Bonzini <pbonzini@redhat.com>]

On 03/12/19 14:16, Thomas Huth wrote:
> On 03/12/2019 14.04, Paolo Bonzini wrote:
>> On 03/12/19 10:15, Thomas Huth wrote:
>>>>>> Maybe we can rename this as read_boot_order_mm, and the previous
>>>>>> read_boot_order_pc as read_boot_order_io.
>>>>>
>>>>> I don't think it makes much sense. This was completely specific to the
>>>>> "prep" machine, even the "40p" machine seems to prefer fw_cfg nowadays.
>>>>> So let's simply remove this old stuff.
>>>>>
>>>>>> diff --git a/tests/endianness-test.c b/tests/endianness-test.c
>>>>>> index 58527952a5..2798802c63 100644
>>>>>> --- a/tests/endianness-test.c
>>>>>> +++ b/tests/endianness-test.c
>>>>>> @@ -35,7 +35,7 @@ static const TestCase test_cases[] = {
>>>>>>        { "mips64", "malta", 0x10000000, .bswap = true },
>>>>>>        { "mips64el", "fulong2e", 0x1fd00000 },
>>>>>>        { "ppc", "g3beige", 0xfe000000, .bswap = true, .superio =
>>>>>> "i82378" },
>>>>>> -    { "ppc", "prep", 0x80000000, .bswap = true },
>>>>>> +    { "ppc", "40p", 0x80000000, .bswap = true },
>>>>
>>>> ... here you access the Super I/O behind the PCI bridge via MMIO?
>>>
>>> The difference is that this is an *arbitrary* address in I/O space
>>> there.
>>
>> No, it's the base address of the ISA space, to which the tests add the
>> address of the pc-testdev device.  It's not any different from the
>> 0x80000000 in boot-order-test.
> 
> Hmm, interesting. Why is it not necessary to set up the BARs of the
> PCI-to-ISA bridge in this case?

I don't know.  Maybe the machine doesn't need it, since these are not
really BARs, since they are positive-decode addresses on the ISA bus.
It may also be an emulation inaccuracy in the pc87312 ISA bridge.

Paolo

>> That said, I think it's a sensible objection that boot order doesn't
>> come from m48t59 on 40p (does it not?).
> Right. I'm also not an expert here, but I think the OpenBIOS on 40p
> rather uses fw_cfg instead.
> 
>  Thomas
>