[yocto] packagegroup-core-boot failure for RTC-less system

[Jon Szymaniak]

>> I have a MACHINE_FEATURES which *does not* include "rtc", as the platform I
>> am working on doesn't have an RTC.
>>
>> The busybox bbappend I'm using (attached below) uses the provided
>> defconfig, but
>> disables the HWCLOCK features.
>>
>> However, my build is failing due to packagegroup-core-boot being unable to
>> meet the busybox-hwclock dependency. Looking at this line from
>> packagegroup-core-boot.bb, it seems to me that busybox-hwlock shouldn't be
>> getting placed in the core-boot's RDEPENDS, given that my MACHINE_FEATURES
>> does not include "rtc":
>>
>>     ${@base_contains("MACHINE_FEATURES", "rtc", "busybox-hwclock", "", d)} \
>>
>>
>> Any thoughts or tips on debugging this? Perhaps there's somewhere I can
>> stick a print of MACHINE_FEATURES to verify that it is what I thought I
>> set?
>
> The way to query the final value of MACHINE_FEATURES is:
>
> bitbake -e | grep ^MACHINE_FEATURES=
>
> FYI though, rtc is a "backfilled" feature - because it was introduced later on
> and we didn't want to break existing machines that do have an RTC and don't
> yet have "rtc" in MACHINE_FEATURES, we added it to MACHINE_FEATURES_BACKFILL.
> In order to prevent it from being backfilled, you can add the following to your
> machine config:
>
> MACHINE_FEATURES_BACKFILL_CONSIDERED = "rtc"
>
> Cheers,
> Paul
>
> --
>
> Paul Eggleton
> Intel Open Source Technology Centre

Hi Paul,

That certainly does the trick!

I didn't realize this "backfill" concept had been added, but now see
it's very well-documented
in the 1.3 manual. Funny how easy it is to find things once you know
what you're looking for... :)

Many thanks!
Jon