Re: [PATCH 4/6] Enable proper rebuilds on dependency changes

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2018-02-13 20:02, Alexander Smirnov wrote:
> 
> On 02/13/2018 09:44 PM, Jan Kiszka wrote:
>> On 2018-02-13 19:08, Alexander Smirnov wrote:
>>> On 02/13/2018 08:57 PM, Jan Kiszka wrote:
>>>> On 2018-02-13 17:21, Jan Kiszka wrote:
>>>>> On 2018-02-13 14:03, Alexander Smirnov wrote:
>>>>>> On 02/12/2018 10:59 AM, Jan Kiszka wrote:
>>>>>>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>>>>>>
>>>>>>> Install a basichash as signature handler and set the stamp policy to
>>>>>>> full - and suddenly we get proper rebuilds of the image and all
>>>>>>> affected
>>>>>>> packages when some recipe down the dependency chain changed!
>>>>>>>
>>>>>>> We are using the legacy bitbake mechanism here as we do not have
>>>>>>> setscene machinery like OE. Still good enough for us.
>>>>>>>
>>>>>>
>>>>>> BTW: have you tried this? Two years ago I tried it in Yocto and it
>>>>>> didn't work properly, not all the dependents were rebuilt. If it
>>>>>> works,
>>>>>> it's a very good feature!
>>>>>
>>>>> Yes, I'm using it since this weekend for both Isar as well as
>>>>> jailhouse-images development, and it helped a lot already. The only
>>>>> limitation I found, but I do not remember right now if that isn't
>>>>> inherent to bitbake, is that it does not detect changes in files that
>>>>> the recipes carries in its SRC_URI (file://...). Then you need "-c
>>>>> clean" for the affected target - which now works as well.
>>>>>
>>>>
>>>> Found another issue, which worked surprisingly well so far despite
>>>> being
>>>> fairly broken: do_setup_mounts is not re-run on rebuilds.
>>>
>>> Investigating exactly this issue. It occures for clean builds also. My
>>> guess is patch #3, currently I'm building with only 2 first applied.
>>> With 3rd one applied build failed.
>>>
>>
>> That's not the right approach, the concept of the setup_mounts task is
>> broken.
> 
> Why you think it's broken? Just tested, it works good:

It's broken in its design: you stamp a task and then remove that stamp
again on restarts. That only works because we didn't generate the full
dependency chain. Once you do, all dependent tasks we be kicked for
re-run. Removing patch 3 is voodoo debugging. I bet you can't explain
why that works around the issue, and I'm sure it will break eventually
again. Moreover, it's needlessly complex.

The much simpler solution is to try-mount when needed, at user side.
Patch will follow, likely by resending the whole series

Jan

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