[U-Boot] [PATCH] [U-boot]: Change FDT memory typpe from runtime data to acpi reclaim

[Heinrich Schuchardt]

On 4/11/19 9:41 PM, Ilias Apalodimas wrote:
> Hi Heinrich,
>> On 4/11/19 8:39 PM, Ilias Apalodimas wrote:
>>> Following Ard's suggestion:
>>> Runtime data sections are intended for data that is used by the runtime
>>> services implementations.
>>> Let's change they type to EFI_ACPI_RECLAIM_MEMORY
>>>
>>> Suggested-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
>>> Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
>>> ---
>>>   cmd/bootefi.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/cmd/bootefi.c b/cmd/bootefi.c
>>> index 3619a20e6433..b54181909aff 100644
>>> --- a/cmd/bootefi.c
>>> +++ b/cmd/bootefi.c
>>> @@ -111,13 +111,13 @@ static efi_status_t copy_fdt(void **fdtp)
>>>   	new_fdt_addr = (uintptr_t)map_sysmem(fdt_ram_start + 0x7f00000 +
>>>   					     fdt_size, 0);
>>>   	ret = efi_allocate_pages(EFI_ALLOCATE_MAX_ADDRESS,
>>> -				 EFI_RUNTIME_SERVICES_DATA, fdt_pages,
>>> +				 EFI_ACPI_RECLAIM_MEMORY, fdt_pages,
>>
>> GRUB uses EfiLoaderCode when installing its modified version of the FDT.
>>
>> The "Embedded Base Boot Requirements (EBBR) Specification, Release v1.0"
>> does not require ACPI support. Can we expect EfiACPIReclaimMemory to be
>> supported if we do not have any ACPI table?
>>
>> How about functions efi_smbios_register() and efi_acpi_register()?
>>
>> How about systab.tables assigned in efi_initialize_system_table()? Which
>> of the addresses in systab.tables should be updated upon relocation.
>>
>> The EFI Spec is really hazy: "A pointer to the table associated with
>> VendorGuid. Whether this pointer is a physical address or a
>> virtual address during runtime is determined by the VendorGuid."
>>
>> The FDT_TABLE_GUID or DEVICE_TREE_GUID as Linux calls it is not defined
>> in the UEFI spec. So we can marvel about expected behavior. Is there any
>> other document specifying it?
>
> What about using EFI_BOOT_SERVICES_DATA instead of EFI_ACPI_RECLAIM_MEMORY?
> This still fixes the issue and doesn't cause any of the potential problems you
> mentioned

Why services data and not loader data?

As said above we should consider all three supported tables ACPI,
SMBIOS, and FDT when thinking about a fix. The UEFI spec describes that
the addresses inside ACPI and SMBIOS tables are not fixed up when
entering runtime.

This indicates that at least these tables have to be accessible at
runtime. Why do you think that the FDT table should be treated
differently to the ACPI table?

Best regards

Heinrich

>
> Thanks
> /Ilias
>