[yocto] Accelerate kernel module built in eSDK?

[Zhaolong Zhang]

On 2018/12/28 23:01, richard.purdie at linuxfoundation.org wrote:
> On Fri, 2018-12-28 at 22:35 +0800, Zhaolong Zhang wrote:
>> On 2018/12/28 19:40, richard.purdie at linuxfoundation.org wrote:
>>> On Fri, 2018-12-28 at 18:19 +0800, Zhaolong Zhang wrote:
>>>> Hi Experts,
>>>>
>>>> Building out-of-tree kernel modules in eSDK will trigger a new
>>>> rebuilding of kernel, which consumes lots of time.
>>>> Is it possible to cache the do_shared_workdir() task in sstate-
>>>> cache
>>>> and ship it within eSDK? And how?
>>>>
>>>> Or is there other method to accelerate?
>>>>
>>>> Thanks in advance.
>>>
>>> It is possible but it means creating a tarball of all the kernel
>>> source
>>> and build artefacts. Usually its just as quick to extract new
>>> kernel
>>> source and build it than it is to store this and extract it. The
>>> sstate
>>> object would be huge.
>>>
>>
>> Hi Richard,
>>
>> Thanks for responding!
>>
>> Isn't sstate object also a tarball for them? Creating another
>> tarball
>> would be a hacking and how can I let module.bbclass know that the
>> kernel
>> source and build artifact are ready, without sstate hashes?
> 
> My point is that using sstate for this will be slow and mean there is a
> very large sstate object. The performance benefits aren't very clear.
> We used to create an sstate object but it got a lot of complaints about
> speed/performance.

Understood. I'd like to have a try, but don't know how. In the git 
history, I can only find that do_shared_workdir_setscene was 
deliberately disabled.

Regards,
Zhaolong


> 
> Cheers,
> 
> Richard
>