Re: [PATCH v3 1/5] xen: define ACPI and DT device info sections macros

[Jan Beulich <jbeulich@xxxxxxxx>]

On 26.09.2024 11:15, oleksii.kurochko@xxxxxxxxx wrote:
> On Thu, 2024-09-26 at 08:23 +0200, Jan Beulich wrote:
>> On 25.09.2024 18:08, oleksii.kurochko@xxxxxxxxx wrote:
>>> On Wed, 2024-09-25 at 10:36 +0200, Jan Beulich wrote:
>>>> PPC's desire to use DECL_SECTION() can certainly be covered by
>>>> providing
>>>> a (trivial) DECL_SECTION() also for Arm and RISC-V. Seeing that
>>>> even
>>>> x86
>>>> overrides the default to the trivial form for building xen.efi,
>>>> I'm
>>>> inclined to suggest we should actually have a way for an arch to
>>>> indicate
>>>> to xen.lds.h that it wants just the trivial form (avoiding a
>>>> later
>>>> #undef).
>>> If to go with what I suggested before then x86 will look like:
>>>
>>> diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
>>> index d48de67cfd..911585541e 100644
>>> --- a/xen/arch/x86/xen.lds.S
>>> +++ b/xen/arch/x86/xen.lds.S
>>> @@ -3,6 +3,10 @@
>>>  
>>>  #include <xen/cache.h>
>>>  #include <xen/lib.h>
>>> +
>>> +#ifdef EFI
>>> +#define SIMPLE_DECL_SECTION
>>> +#endif
>>>  #include <xen/xen.lds.h>
>>>  #include <asm/page.h>
>>>  #undef ENTRY
>>> @@ -12,9 +16,7 @@
>>>  
>>>  #define FORMAT "pei-x86-64"
>>>  #undef __XEN_VIRT_START
>>> -#undef DECL_SECTION
>>>  #define __XEN_VIRT_START __image_base__
>>> -#define DECL_SECTION(x) x :
>>>  
>>>  ENTRY(efi_start)
>>>  
>>> diff --git a/xen/include/xen/xen.lds.h b/xen/include/xen/xen.lds.h
>>> index a17810bb28..fb11ba7357 100644
>>> --- a/xen/include/xen/xen.lds.h
>>> +++ b/xen/include/xen/xen.lds.h
>>> @@ -5,6 +5,8 @@
>>>   * Common macros to be used in architecture specific linker
>>> scripts.
>>>   */
>>>  
>>> +#ifdef SIMPLE_DECL_SECTION
>>
>> #ifndef I guess?
>>
>>> @@ -15,6 +17,10 @@
>>>  # define DECL_SECTION(x) x : AT(ADDR(x) - __XEN_VIRT_START)
>>>  #endif
>>>  
>>> +#else /* SIMPLE_DECL_SECION */
>>> +# define DECL_SECTION(x) x :
>>> +#endif
>>> +
>>>  /*
>>>   * To avoid any confusion, please note that the EFI macro does not
>>> correspond
>>>   * to EFI support and is used when linking a native EFI (i.e.
>>> PE/COFF)
>>> binary,
>>>
>>> Does it make sense? Or it would be better to follow way for each
>>> architecture:
>>>    #undef DECL_SECTION
>>>    #define DECL_SECTION(x) x :
>>
>> Hard to tell which one's better; I was asking myself that same
>> question
>> when writing an earlier reply. I'm slightly in favor of the form you
>> have
>> now.
> Do you mean moving only a content of section without secname and laddr
> ( in case of x86 and PPC ), and alignment to xen.lds.h ?

No. I was solely referring to the DECL_SECTION() aspect.

Jan