[U-Boot] [PATCH v8 22/30] efi: sandbox: Tidy up copy_fdt() to work with sandbox

[Simon Glass]

Hi Alex,

On 18 June 2018 at 09:00, Alexander Graf <agraf at suse.de> wrote:
> On 06/18/2018 04:08 PM, Simon Glass wrote:
>>
>> At present this function takes a pointer as its argument, then passes this
>> to efi_allocate_pages(), which actually takes an address. It uses casts,
>> which are not supported on sandbox.
>
>
> I think this is the big API misunderstanding that caused our disagreements:
> efi_allocate_pages(uint64_t *memory) gets a uint64_t *address as input
> parameter, but uses the same field to actually return a void * pointer. This
> is the function that really converts between virtual and physical address
> space.
>
> This is the explicit wording of the spec[1] page 168:
>
>   The AllocatePages() function allocates the requested number of pages and
> returns a pointer to the base address of the page range in the location
> referenced by Memory.

The code at present uses *Memory as the address on both input and
output. The spec is confusing, but I suspect that is what it meant.

>
> So yes, we have to cast. There is no other way around it without completely
> creating a trainwreck of the API.

efi_allocate_pages_ext() can do this though. We don't need to copy the
API to efi_allocate_pages().

Of course this is future possible work, we don't need to do it now.

>
>
> Alex
>
> [1]
> http://www.uefi.org/sites/default/files/resources/UEFI%20Spec%202_7_A%20Sept%206.pdf
>

Regards,
Simon