Re: [PATCH v2 1/1] efi_loader: expose the device-tree file name

[Tom Rini <trini@konsulko.com>]

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On Mon, Oct 23, 2023 at 05:37:34PM +0200, Mark Kettenis wrote:
> > From: Simon Glass <sjg@google.com>
> > Date: Mon, 23 Oct 2023 00:08:40 -0700
> > 
> > > > fdt_node_check_compatible() does most of the work...then you need to
> > > > check which FDT has the most specific match (i.e. latest in the string
> > > > list). That handles things like board revisions, variants, etc.
> > > >
> > > > My concern is about adding a feature when there is already a defined
> > > > spec and mechanism for this to work. What happens when we load the
> > > > file and the compatible is wrong?
> > > >
> > > > At best, I see the filename as a hint.
> > > >
> > > > [Perhaps this is the wrong time to ask, but why are kernels +DT not
> > > > shipped in FIT on ARM?]
> > >
> > > FIT is U-Boot specific. For Linux distributions it is easier to use a
> > > firmware agnostic method of booting.
> > 
> > I'd like to suggest that distros use both. Then U-Boot can work as it
> > was designed and we can avoid these work-arounds.
> > 
> > FIT is actually implemented in various other bootloaders. In fact
> > perhaps grub is the only one that doesn't? I can't think of any
> > others.
> 
> Simon, please stop pushing this.  OpenBSD's bootloader does not
> support FIT and we have no interest in supporting it.  Our users
> expect to be able to just copy a new kernel in place and use it and
> our OS upgrade procedure depends on this as well.  And this is
> incompatble with FIT.  I've explained this about a dozen times to you
> now.

In the context of this thread, genuinely, how will OpenBSD (and the rest
of the BSD families) operate? I agree U-Boot doesn't want to have to
know all of the UFSes, so that means the SCT will be populated either by
the DT passed to U-Boot, or the DT we were built with. Is it that since
the next stage is an EFI app, it will check that variable and use that
hint?

-- 
Tom

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