Re: [PATCH v2 5/5] xen/common: move device initialization code to common code

[Jan Beulich <jbeulich@xxxxxxxx>]

On 24.09.2024 12:16, oleksii.kurochko@xxxxxxxxx wrote:
> On Mon, 2024-09-23 at 16:43 +0200, Jan Beulich wrote:
>> On 17.09.2024 18:15, Oleksii Kurochko wrote:
>>> --- a/xen/common/Kconfig
>>> +++ b/xen/common/Kconfig
>>> @@ -12,6 +12,14 @@ config CORE_PARKING
>>>     bool
>>>     depends on NR_CPUS > 1
>>>  
>>> +config DEVICE_INIT
>>> +   bool
>>> +   default !X86
>>
>> This can simply be "def_bool y" as ...
>>
>>> +   depends on !X86 && (ACPI || HAS_DEVICE_TREE)
>>
>> ... this enforces all restrictions. As indicated before I'd prefer if
>> we
>> could get away without yet another Kconfig constant, which would then
>> also eliminate my concern about the expression not really covering
>> for
>> the case where x86 would obtain DT support (and hence likely needing
>> the
>> initialization here, too). What about ...
>>
>>> --- a/xen/common/Makefile
>>> +++ b/xen/common/Makefile
>>> @@ -6,6 +6,7 @@ obj-$(CONFIG_HYPFS_CONFIG) += config_data.o
>>>  obj-$(CONFIG_CORE_PARKING) += core_parking.o
>>>  obj-y += cpu.o
>>>  obj-$(CONFIG_DEBUG_TRACE) += debugtrace.o
>>> +obj-$(CONFIG_DEVICE_INIT) += device.o
>>
>> obj-$(CONFIG_HAS_DEVICE_TREE) += device.o
>> obj-$(filter-out $(CONFIG_X86),$(CONFIG_ACPI)) += device.o
>>
>> ? (Eventually we could then simplify this to just obj-$(CONFIG_ACPI),
>> to allow DT on x86, making sure the ACPI part of the file builds for
>> x86 but does nothing there.)
> I am okay with this solution. It seems I misunderstood you in the first
> version of this patch series. When "obj-$(or ... )" was used, I decided
> it wasn’t a good approach to use 'or', 'filter-out', or other similar
> functions in Makefiles for such cases. I couldn't come up with a better
> solution at the time, so I introduced a new config instead.
> 
> The only issue I see with this approach is that in device.c, there is
> the following code:
>    #ifdef CONFIG_ACPI
>    
>    extern const struct acpi_device_desc _asdevice[], _aedevice[];
>    
>    int __init acpi_device_init(enum device_class class, const void *data,
>    int class_type)
>       ...
>    
>    #endif
> This shouldn't be compiled for X86. However, it will still be compiled
> if we simplify to:
>    obj-$(CONFIG_HAS_DEVICE_TREE) += device.o
>    obj-$(CONFIG_ACPI) += device.o

Which is why I said "eventually". For now it'll be the $(filter-out ...).
How to best adjust the code to permit above simplification is to be
determined; what you outlined matches what I had thought of as an option.

Jan