Re: [PATCH v4 2/3] arm/efi: Use dom0less configuration when using EFI boot

[Luca Fancellu <luca.fancellu@arm.com>]

> On 1 Oct 2021, at 15:22, Jan Beulich <jbeulich@suse.com> wrote:
> 
> On 01.10.2021 15:55, Luca Fancellu wrote:
>>> On 1 Oct 2021, at 12:02, Jan Beulich <jbeulich@suse.com> wrote:
>>> On 30.09.2021 16:28, Luca Fancellu wrote:
>>>> @@ -1361,12 +1361,30 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
>>>>        efi_bs->FreePages(cfg.addr, PFN_UP(cfg.size));
>>>>        cfg.addr = 0;
>>>> 
>>>> -        dir_handle->Close(dir_handle);
>>>> -
>>>>        if ( gop && !base_video )
>>>>            gop_mode = efi_find_gop_mode(gop, cols, rows, depth);
>>>>    }
>>>> 
>>>> +#ifdef CONFIG_HAS_DEVICE_TREE
>>>> +    /* Get the number of boot modules specified on the DT or an error (<0) */
>>>> +    dt_modules_found = efi_arch_check_dt_boot(dir_handle);
>>>> +#endif
>>> 
>>> So I had asked to add a stub enclosed in such an #ifdef, to avoid the
>>> #ifdef here. I may be willing to let you keep things as you have them
>>> now, but I'd like to understand why you've picked that different
>>> approach despite the prior discussion.
>> 
>> There must be a misunderstanding, your message in the v3 was:
>> 
>> "Every time I see this addition I'm getting puzzled. As a result I'm
>> afraid I now need to finally ask you to do something about this (and
>> I'm sorry for doing so only now). There would better be no notion of
>> DT in x86 code, and there would better also not be a need for
>> architectures not supporting DT to each supply such a stub. Instead
>> I think you want to put this stub in xen/common/efi/boot.c, inside a
>> suitable #ifdef.”
>> 
>> So I thought you wanted me to remove the stub in x86 (since it doesn’t support DT)
>> and put this call under #ifdef so it won’t be compiled for arch not supporting DT.
> 
> So FTAOD I'll repeat the crucial part: "I think you want to put this
> stub in xen/common/efi/boot.c". There was nothing about removing the
> stub altogether.

Oh ok, now I see, so in your opinion this is a better idea:

#ifndef CONFIG_HAS_DEVICE_TREE
static inline int __init efi_arch_check_dt_boot(EFI_FILE_HANDLE dir_handle)
{
    return 0;
}
#endif

But I would like to understand the advantage respect of my approach, could you
explain me?

Cheers,
Luca


> 
> Jan
>