[U-Boot] [PATCH v2 4/8] x86: Tidy up selection of building the EFI stub

[Simon Glass]

Hi Bin,

On 27 September 2016 at 19:23, Bin Meng <bmeng.cn at gmail.com> wrote:
> Hi Simon,
>
> On Wed, Sep 28, 2016 at 1:55 AM, Simon Glass <sjg at chromium.org> wrote:
>> Hi Bin,
>>
>> On 26 September 2016 at 20:44, Bin Meng <bmeng.cn at gmail.com> wrote:
>>> Hi Simon,
>>>
>>> On Tue, Sep 27, 2016 at 8:35 AM, Simon Glass <sjg at chromium.org> wrote:
>>>> Hi Bin,
>>>>
>>>> On 26 September 2016 at 02:50, Bin Meng <bmeng.cn at gmail.com> wrote:
>>>>> Hi Simon,
>>>>>
>>>>> On Mon, Sep 26, 2016 at 5:27 AM, Simon Glass <sjg at chromium.org> wrote:
>>>>>> At present we use a CONFIG option in efi.h to determine whether we are
>>>>>> building the EFI stub or not. This means that the same header cannot be
>>>>>> used for EFI_LOADER support. The CONFIG option will be enabled for the
>>>>>> whole build, even when not building the stub.
>>>>>>
>>>>>> Use a different define instead, set up just for the files that make up the
>>>>>> stub.
>>>>>>
>>>>>> Signed-off-by: Simon Glass <sjg at chromium.org>
>>>>>> ---
>>>>>>
>>>>>> Changes in v2:
>>>>>> - Add new patch to tidy up selection of building the EFI stub
>>>>>>
>>>>>>  include/efi.h    | 7 +++++--
>>>>>>  lib/efi/Makefile | 4 ++--
>>>>>>  2 files changed, 7 insertions(+), 4 deletions(-)
>>>>>>
>>>>>> diff --git a/include/efi.h b/include/efi.h
>>>>>> index d07187c..3d58780 100644
>>>>>> --- a/include/efi.h
>>>>>> +++ b/include/efi.h
>>>>>> @@ -30,8 +30,11 @@ struct efi_device_path;
>>>>>>
>>>>>>  #define EFI_BITS_PER_LONG      BITS_PER_LONG
>>>>>>
>>>>>> -/* With 64-bit EFI stub, EFI_BITS_PER_LONG has to be 64 */
>>>>>> -#ifdef CONFIG_EFI_STUB_64BIT
>>>>>> +/*
>>>>>> + * With 64-bit EFI stub, EFI_BITS_PER_LONG has to be 64. EFI_STUB is set
>>>>>> + * in lib/efi/Makefile, when building the stub.
>>>>>> + */
>>>>>> +#if defined(CONFIG_EFI_STUB_64BIT) && defined(EFI_STUB)
>>>>>
>>>>> I don't understand why this is needed?
>>>>
>>>> If building the 64-bit EFI stub, we need to use 64-bit ints for the
>>>> stub, but 32-bits for the rest of U-Boot. So this header gets used
>>>> both ways.
>>>>
>>>
>>> For 32-bit EFI stub or U-Boot itself, EFI_BITS_PER_LONG is defined as
>>> BITS_PER_LONG which is 32.
>>
>> Yes that's right. But in the case of the stub, it can be different
>> from U-Boot itself. This case takes care of that.
>>
>
> Sorry but I still don't get it. What's broken without this change?

When building U-Boot with CONFIG_EFI_STUB_64BIT enabled, at present
EFI_BITS_PER_LONG will be 64.

This is fine for building the stub.

But for building U-Boot, we still want it to be 32.

At present the code overrides EFI_BITS_PER_LONG, setting it to 64 if
CONFIG_EFI_STUB_64BIT is enabled.

This means that EFI_LOADER support does not build properly, since it
uses 64 instead of 32.

You can try building without this commit to see the result.

Regards,
Simon