[U-Boot] [PATCH 2/2] x86: Allow 32-bit toolchain to compile 64-bit U-Boot

[Bin Meng]

Hi Andy,

On Sun, Jul 23, 2017 at 8:51 PM, Andy Shevchenko
<andy.shevchenko at gmail.com> wrote:
> On Sun, Jul 23, 2017 at 1:48 PM, Bin Meng <bmeng.cn at gmail.com> wrote:
>> On Sun, Jul 23, 2017 at 6:36 PM, Andy Shevchenko
>> <andy.shevchenko at gmail.com> wrote:
>>> On Sun, Jul 23, 2017 at 1:26 PM, Bin Meng <bmeng.cn at gmail.com> wrote:
>>>> On Sun, Jul 23, 2017 at 6:07 PM, Andy Shevchenko
>>>> <andy.shevchenko at gmail.com> wrote:
>
>>>> Sure. Reword it as "Allow toolchains that are pre-configured to build
>>>> 32-bit codes to compile 64-bit U-Boot"?
>>>
>>> Hmm... The flag you are adding does enforce or allow?
>>> So, if -m64 will still allow to compile 32-bit code, then it's
>>> allowing, otherwise it's enforcing.
>>> Or I miss something?
>>
>> -m64 will only be passed to compiler when building source files that
>> are part of 64-bit U-Boot. For 32-bit U-Boot, it is still -m32.
>
> Yes, what I'm trying to understand is
> 1. U-Boot is compiled _either_ 64-bit, _or_ 32-bit binary -- correct?

64-bit U-Boot image is a combination of 32-bit U-Boot (SPL) plus
64-bit U-Boot (proper). For the U-Boot proper, it has be compiled with
64-bit and currently -m64 is missing, primary due to the toolchain we
previously used has implicitly -m64 configured.

> 2. If above is correct then -m64 _enforces_ to compile it as 64-bit -- correct?
>

Correct.

> Or I'm mistaken with the last and -m64 just adds a _preference_ to
> compile as 64-bit?
>

Regards,
Bin