Hi Alex,
On 21 June 2018 at 04:13, Alexander Graf agraf@suse.de wrote:
On 06/21/2018 04:01 AM, Simon Glass wrote:
Hi Alex,
On 18 June 2018 at 09:00, Alexander Graf agraf@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.
The spec means *Memory on IN is an address, on OUT is a pointer. It's quite clear on that. Since the functions is available to payloads, we should follow that semantic.
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().
Yikes. There's no way we'll create a frankenstein not-really-almost EFI API inside U-Boot. Either we stick to the standard or we don't.
The API is the _ext() function, right? We can rename the internal function if you like.
In any case I think you have this confused. From the spec:
"Pointer to a physical address. On input, the way in which the address is used depends on the value of Type. See “Description” for more information. On output the address is set to the base of the page range that was allocated. See “Related Definitions.”"
The parameter does not turn into a pointer on exit. It is an address, just as it is on input. What am I missing?
Regards, Simon