[Sound-open-firmware] Linux build for arm64

[Pierre-Louis Bossart]

On 7/18/19 3:04 PM, Daniel Baluta wrote:
> On Thu, Jul 18, 2019 at 10:57 PM Pierre-Louis Bossart
> <pierre-louis.bossart at linux.intel.com> wrote:
>>
>>
>>
>> On 7/18/19 2:27 PM, Daniel Baluta wrote:
>>> Hi Liam  / Pierre,
>>>
>>> Could we add a build for arm64 too in CI? With recent patches that
>>> add support for i.MX8 SOF Linux driver it would be handy to also
>>> have the build for arm64.
>>>
>>> I can help you with the cross-compilers and build instructions.
>>>
>>> Currently we are only building for x86_64.
>>>
>>> https://travis-ci.org/thesofproject/linux/builds/560509972
>>
>> Sure, I see no issue, as long as it's just compilation it's almost free.
>> hardware-tests are probably out-of-scope as discussed some time back.
>>
>> the main point will be to agree on which kernel config you want to use.
>> To speed things up, we use a minimal kernel based on defconfig and
>> Kconfig fragments, so that changes are automatically applied. see
>> https://github.com/thesofproject/kconfig. if we have a imx-defconfig
>> fragment file then we can add support very quickly.
>>
>> I use this for my own 'maintainer' tests where I compile locally with
>> make.cross for multiple architectures, see script attached.
> 
> That's great! I will have a look at your scripts and provide some info
> tomorrow. In the arm64 world there are no separate board defconfigs.
> 
> There is one huge defconfig with everything enabled in
> linux/arch/arm64/configs/defconfig.
> So, I will trim this down to speed up compilation.

FWIW, the kernel compilation for all SOF/x86_64 targets takes about 4mn 
on a Skylake NUC and less than 1mn on a xeon server. This is the sort of 
target we'd be looking for so that CI isn't too slow (actually 
compilation time can be dwarfed by Github/network sluggishness).