Re: [PATCH v5 8/8] hw/mem/cxl_type3: Add CXL RAS Error Injection Support.

[Markus Armbruster]

Thomas Huth <thuth@redhat.com> writes:

> On 22/02/2023 19.16, Philippe Mathieu-Daudé wrote:
>> +Thomas (meson) & Marc-André (conditional QAPI)
>
> + Markus
>
>> On 22/2/23 17:49, Jonathan Cameron wrote:

[...]

>>>>>> Doesn't these need
>>>>>>
>>>>>>         'if': 'CONFIG_CXL_MEM_DEVICE',
>>>>>>
>>>>>> ?
>>>>>
>>>>> If I make this change I get a bunch of
>>>>>
>>>>> ./qapi/qapi-types-cxl.h:18:13: error: attempt to use poisoned 
>>>>> "CONFIG_CXL_MEM_DEVICE"
>>>>>      18 | #if defined(CONFIG_CXL_MEM_DEVICE)
>>>>
>>>> Err, I meant the generic CONFIG_CXL, not CONFIG_CXL_MEM_DEVICE.
>>>>
>>>>> It's a target specific define (I think) as built alongside PCI_EXPRESS
>>>>> Only CXL_ACPI is specifically included by x86 and arm64 (out of tree)
>>>>>
>>>>> To be honest though I don't fully understand the QEMU build system so the 
>>>>> reason
>>>>> for the error might be wrong.
>>>>
>>>> You need to restrict to system emulation (the 'have_system' check):
>>>
>>> This doesn't help - still have
>>> attempt to used poisoned "CONFIG_CXL"
>
> Not sure how the QAPI generator works, but target specific config switches 
> can only be used in target specific json files there, so that's 
> machine-target.json and misc-target.json currently, as far as I know. Not 
> sure how the QAPI generator distinguishes between common and target specific 
> code, though ... just by the "-target" suffix? Maybe Markus or Marc-André can 
> comment on that.

Whenever you use a poisoned macro in a conditional, all the code
generated for this .json file (we call it a "QAPI schema module")
becomes target-dependent.  The QAPI code generator itself is blissfully
unaware of this.

Since target-dependent code needs to be compiled differently, the build
process needs to be know which modules are target-dependent.  We do this
in one of the stupidest ways that could possibly work: a module is
target-dependent if its name ends with "-target".  There are just two
right now: qapi/machine-target.json and qapi/misc-target.json.

The logic resides in qapi/meson.build.  Look for

    if module.endswith('-target')

Questions?

[...]