Re: [PATCH v2 2/2] xen: Populate xen.lds.h and make use of its macros

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.03.2022 12:32, Julien Grall wrote:
> On 29/03/2022 12:42, Jan Beulich wrote:
>> On 29.03.2022 12:54, Julien Grall wrote:
>>> On 29/03/2022 11:12, Michal Orzel wrote:
>>>> On 29.03.2022 11:54, Julien Grall wrote:
>>>>> On 22/03/2022 08:02, Michal Orzel wrote:
>>>>>> --- a/xen/include/xen/xen.lds.h
>>>>>> +++ b/xen/include/xen/xen.lds.h
>>>>>> @@ -5,4 +5,104 @@
>>>>>>      * Common macros to be used in architecture specific linker scripts.
>>>>>>      */
>>>>>>     +/* Macros to declare debug sections. */
>>>>>> +#ifdef EFI
>>>>>
>>>>> AFAIK, we don't define EFI on Arm (just CONFIG_EFI). Yet we do support 
>>>>> EFI on arm64.
>>>>>
>>>>> As this #ifdef is now in generic code, can you explain how this is meant 
>>>>> to be used?
>>>>>
>>>> As we do not define EFI on arm, all the stuff protected by #ifdef EFI is 
>>>> x86 specific.
>>>
>>> I find the name "EFI" too generic to figure out that this code can only
>>> be used by x86.
>>>
>>> But, from my understanding, this header is meant to contain generic
>>> code. It feels a bit odd that we are moving arch specific code.
>>>
>>> To be honest, I don't quite understand why we need to make the
>>> diffferentiation on x86. So I guess the first question is how this is
>>> meant to be used on x86?
>>
>> We produce two linker scripts from the single source file: One (with EFI
>> undefined) to link the ELF binary, and another (with EFI defined) to link
>> the PE/COFF output. If "EFI" is too imprecise as a name for the identifier,
>> I wouldn't mind renaming it (to PE_COFF?), but at the same time I'm not
>> convinced this is really necessary.
> 
> Thank for the explanation (and the other ones in this thread). You are 
> right the confusion arised from "generating" vs "linking".
> 
> Renaming to PE_COFF may help to avoid the confusion with CONFIG_EFI. 
> That said, it would possibly make more difficult to associate the flag 
> with "linking an EFI binary".

Indeed. And EFI_PE_COFF is getting a little unwieldy for my taste.

> I think some documentaion about the define EFI would be help so there 
> are no more confusion between CONFIG_EFI/EFI. But I am not sure where to 
> put it. Maybe at the top of the header?

That's perhaps the best place, yes.

Jan