Invalid build with change in PLATFORM and no clean

[E Shattow]

Hello,

I have narrowed down a strange behavior from U-Boot which may be worth
sharing, related to OpenSBI.

Steps to reproduce:

1. (OpenSBI) checkout opensbi v1.7

2. (OpenSBI) make

3. (OpenSBI) make PLATFORM=generic

when U-Boot v2025.10-rc4 links to opensbi:
4. (U-Boot) make starfive_visionfive2_defconfig:
5. (U-Boot) make OPENSBI=/path/to/fw_payload.bin

the result of U-Boot `reset` command is:

StarFive # reset

resetting ...

System reset not supported on this platform

### ERROR ### Please RESET the board ###

6. (OpenSBI) make PLATFORM=generic clean ; make PLATFORM=generic

7. (U-Boot) make OPENSBI=/path/to/fw_payload.bin

result of U-Boot `reset` command is normal, system resets and does not
complain.

Can this be improved in the OpenSBI build system?  It is difficult to
figure out that OpenSBI needs a make clean from the symptom;  I thought
that it might be some devicetree property or unknown in U-Boot, but
after hours trying to git bisect U-Boot that was not it at all, it's the
dependency tracking in OpenSBI build system not catching the change in
PLATFORM.

Best regards,

-E Shattow (not on the list please CC/reply-all thank you!)