[U-Boot] [PATCH v2 00/11] SiFive FU540 Support

[Auer, Lukas]

On Sat, 2019-02-02 at 09:06 -0800, Paul Walmsley wrote:
> On Tue, 22 Jan 2019, Auer, Lukas wrote:
> 
> > For the same reason, I agree with you that it does not make sense
> > to 
> > implement the SBI in U-Boot. OpenSBI is better suited to handle
> > this.
> 
> It should be possible to link the OpenSBI library with U-boot, then
> allow 
> U-boot to use SBI services itself, and to expose the SBI services to 
> whatever it boots.  So the OpenSBI boot firmware wouldn't be used,
> but the 
> underlying library code would be.  That simplifies the boot flow,
> since 
> the (separate) OpenSBI firmware would no longer be needed.
> 

Yes, that would also work. I am not at all against integrating the
OpenSBI library into U-Boot. Having a separate SBI implementation
instead of a shared one (OpenSBI) is what I think does not make sense.

Thanks,
Lukas

> > A boot flow that could be used in this case is the following.
> > 
> > ZSBL -> U-Boot SPL (M-mode) -> OpenSBI -> U-Boot proper (S-mode)
> 
> There are other boot flows that are common on ARM platforms:
> 
> - Boot ROM -> SPL -> U-boot -> Linux
> - Boot ROM -> SPL -> U-boot -> (SBI implementation / TEE) -> Linux
> 
> It would be good if we could avoid prejudicing against any of these
> boot 
> flows.
> 
> 
> - Paul