[U-Boot] [PATCH 2/2] sandbox: Convert SANDBOX_BITS_PER_LONG to Kconfig

[Bin Meng]

Hi Simon,

On Sun, Aug 13, 2017 at 11:35 PM, Simon Glass <sjg at chromium.org> wrote:
> Hi Bin,
>
> On 6 August 2017 at 03:13, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Hi Simon,
>>
>> On Sun, Aug 6, 2017 at 1:16 PM, Simon Glass <sjg at chromium.org> wrote:
>>> Hi Bin,
>>>
>>> On 3 August 2017 at 18:17, Bin Meng <bmeng.cn at gmail.com> wrote:
>>>> Hi Simon,
>>>>
>>>> On Thu, Aug 3, 2017 at 11:24 PM, Simon Glass <sjg at chromium.org> wrote:
>>>>> Hi Bin,
>>>>>
>>>>> On 1 August 2017 at 17:33, Bin Meng <bmeng.cn at gmail.com> wrote:
>>>>>> Convert SANDBOX_BITS_PER_LONG to Kconfig and assign it a correct
>>>>>> number depending on which host we are going to build and run.
>>>>>>
>>>>>> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
>>>>>> ---
>>>>>>
>>>>>>  arch/sandbox/Kconfig         | 5 +++++
>>>>>>  board/sandbox/README.sandbox | 7 +++----
>>>>>>  scripts/config_whitelist.txt | 1 -
>>>>>>  3 files changed, 8 insertions(+), 5 deletions(-)
>>>>>
>>>>> Reviewed-by: Simon Glass <sjg at chromium.org>
>>>>>
>>>>> Is it OK to build 64-bit sandbox on a 32-bit machine? Does that actually work?
>>>>>
>>>>> If then I think we need a 3-way setting like:
>>>>>
>>>>> - 32-bit
>>>>> - 64-bit
>>>>> - native (i.e. whatever the host is)
>>>>
>>>> That means cross-compiling sandbox. So far this is not working. I will
>>>> take a look.
>>>
>>> Or perhaps we just require it to use the bit size of the host? Does
>>> compiling 64-bit U-Boot on a 32-bit machine actually work?
>>>
>>
>> I have not looked into that further but I suspect there is more work
>> than the bit size of the host, for example, linking 64-bit vs. 32-bit
>> libraries?
>
> But does it compile 64-bit sandbox OK on a 32-bit machine? I would
> have thought it would complain.
>

No. Compiling 64-bit sandbox never worked on a 32-bit machine. So far
sandbox build only supports:

1). build from a 32-bit host and run from a 32-bit host
2). build from a 64-bit host and run from a 64-bit host (current
default setting)

> I'm not really asking for this feature, it's just that I don't
> understand how your patch works, and don't necessarily want to lose
> the ability to build a 32-bit sandbox. It is to some extent a helpful
> build/unit test for 32-bit boards which we still have many of.
>

This patch does not introduce any functional changes. It just converts
SANDBOX_BITS_PER_LONG to Kconfig so that this can be changed from
defconfigs or 'make menuconfig' to make it more user friendly if we
are building (a 32-bit) sandbox on a 32-bit host. Ideally we should
add such cross-build functionality to sandbox build.

Regards,
Bin