On 11.02.21 14:02, Tom Rini wrote:
On Thu, Feb 11, 2021 at 12:14:51PM +0100, Ahmad Fatoum wrote:
I think platforms like the STM32MP1 should be handled specially, because they support having an external device tree passed from the FSBL at runtime. See https://github.com/trini/u-boot/blob/master/arch/arm/mach-stm32mp/boot_param...
@Patrick, wouldn't this change break booting newer U-Boot with older TF-A in some configurations? Or is this reusing-fsbl-fdt feature unused?
The long stated policy of U-Boot is to allow non-final bindings to be used until they're finalized in Linux in order to address the "chicken and egg" problem, since it's already a terrible idea to go to production with a Linux kernel that's using non-final bindings. Any older TF-A that doesn't work with this newer binding should be on a developer board and they can just upgrade. Linux says "DT is ABI" and allows the ABI to break when there's a bug in the DT. We don't say "DT is ABI" we say "we use the Linux kernel binding".
I see. Thanks for the clarification.
I am still curious what configurations use the TF-A-provided device tree for U-Boot. Patrick?