On Mon, May 06, 2024 at 01:13:00PM +0200, Francesco Dolcini wrote: > Hello all, > > On Wed, May 01, 2024 at 09:18:01PM +0000, Humphreys, Jonathan wrote: > > Problem statement: > > ================== > > > > Device trees are in theory a pure description of the hardware, and since > > the hardware > > doesn't change, the device tree describing the hardware likewise never > > changes. > > With this, a device tree could then be burned into the hardware's ROM to be > > queried by software for hardware discovery. > > I would like to add another use case that I do not see mentioned here. > > In case of SoM (System On Module) the system can be designed in such a > way that the firmware does not really need to know the complete hardware > description, but only the hardware subset relevant for booting and > the initial hardware configuration is required. > > However the operating system would need the complete hardware > description, that is made of a SoM plus a carrier/base board, to properly > work. > > From a life cycle point of view the firmware of the SoM is going to be > available and written to the board before the actual whole hardware is > even existing and I would not expect to force the SoM user to > update/customize the firmware.
FWIW, my expectation and experiences are the opposite. Using the firmware stack for the SoM unmodified and expecting the OS to get to and then use the correct device tree isn't likely. I'm sure there will be cases where it can (and does today) work, but that's not going to be the case every time. -- Tom _______________________________________________ boot-architecture mailing list -- boot-architecture@lists.linaro.org To unsubscribe send an email to boot-architecture-le...@lists.linaro.org
