Re: [PATCH v3] xen: Add Darwin.mk for GNU toolchains

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.02.2026 14:34, Bertrand Marquis wrote:
>> On 6 Feb 2026, at 14:29, Roger Pau Monné <roger.pau@xxxxxxxxxx> wrote:
>> On Fri, Feb 06, 2026 at 11:38:02AM +0100, Jan Beulich wrote:
>>> On 06.02.2026 09:17, Bertrand Marquis wrote:
>>>> --- /dev/null
>>>> +++ b/config/Darwin.mk
>>>> @@ -0,0 +1,7 @@
>>>> +# Use GNU tool definitions as the tools we are using are either GNU 
>>>> compatible
>>>> +# or we only use features which are supported on Mac OS.
>>>> +include $(XEN_ROOT)/config/StdGNU.mk
>>>> +
>>>> +# Xen uses Linux'es ABI so we are cross compiling on Mac OS.
>>>> +# Force COMPILE_ARCH to a fake value to make sure it is always the case.
>>>> +XEN_COMPILE_ARCH = Darwin
>>>
>>> I first wondered why you say "fake", seeing the file is named Darwin.mk. But
>>> in Config.mk's cross-compile check the build host OS doesn't even matter. So
>>> yes, it needs faking here for the time being.
>>
>> Hm, setting it to "Darwin" seems weird to me.  I understand the
>> purpose of this is to force the user to set XEN_TARGET_ARCH
>> explicitly.  I however wouldn't see it as fully uncorrect to not set
>> this.  It will then execute `uname -m` and get `arm64` back for Apple
>> silicon macs (which is kind of OK?).  Other I suggest we use a non-OSX
>> specific value here, so that if required we could distinguish this
>> case where the user is expected to provide XEN_COMPILE_ARCH.
>>
>> Maybe XEN_COMPILE_ARCH = { unknown | undefined }?
> 
> I am ok to change this with either but maybe unsupported could be
> a third choice?

If I ran into "unsupported" there, I'd wonder if I even should trust any of
this and try it out. I'd prefer either of Roger's suggestions, in the order
given.

Jan