[U-Boot] Buildman Kconfig issue with consecutive builds

[Schrempf Frieder <frieder.schrempf@kontron.de>]

On 07.11.19 15:02, Bin Meng wrote:
> Hi Frieder,
> 
> On Thu, Nov 7, 2019 at 9:28 PM Schrempf Frieder
> <frieder.schrempf@kontron.de> wrote:
>>
>> Hi Bin,
>>
>> On 07.11.19 13:41, Bin Meng wrote:
>>> Hi Schrempf,
>>>
>>> On Thu, Nov 7, 2019 at 12:17 AM Schrempf Frieder
>>> <frieder.schrempf@kontron.de> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I'm having some trouble using buildman to test the impact of some
>>>> Kconfig cleanup patches ([1]).
>>>>
>>>> The patches introduce a new CONFIG_SPL_* option and I try to find out
>>>> which defconfigs need to be fixed, by comparing build sizes.
>>>>
>>>> Now when I added a patch to fix a defconfig I noticed that buildman
>>>> wouldn't report the expected size changes and upon looking more closely
>>>> I found that the added Kconfig options are still missing in u-boot-spl.cfg.
>>>>
>>>> The strange thing is, that when I try to build only the last commit then
>>>> the Kconfig options are there, which is why I suspect a bug in buildman
>>>> not handling Kconfig changes correctly with consecutive builds.
>>>>
>>>> Can anyone have a look what is wrong or how I can debug this issue?
>>>>
>>>> The issue can be reproduced with the branch at [1], running:
>>>>
>>>> buildman -b spi_flash_kconfig_cleanup_3 --step 0 xilinx_zynqmp_virt
>>>>
>>>
>>> Could you please add "-C" to the buildman command line and have a try?
>>
>> Indeed forcing the reconfig between the build steps with '-C' fixes the
>> issue.
>>
>> Is it a known problem, that buildman doesn't handle Kconfig changes
>> correctly without '-C' in some cases?
> 
> AFAIK, this is an intended design of calling buildman w/o '-C' to save
> some build time.

Ok, if that's the case I will try to come up with a patch that adds a 
note to the README. This has cost me a few hours because I was thinking 
buildman does the right thing and Kconfig options are messed up somewhere.