[PATCH 1/2] bloblist: fix the overriding of fdt from bloblist

[Simon Glass]

Hi Raymond,

On Fri, 28 Mar 2025 at 08:17, Raymond Mao <raymond.mao at linaro.org> wrote:
>
> Hi Simon,
>
> On Fri, 28 Mar 2025 at 07:34, Simon Glass <sjg at chromium.org> wrote:
> >
> > Hi Raymond,
> >
> > On Thu, 27 Mar 2025 at 17:13, Raymond Mao <raymond.mao at linaro.org> wrote:
> > >
> > > When a bloblist is valid and contains fdt, it explicitly means
> > > a previous boot stage is passing transfer list compliant with
> > > Firmware Handoff specification, thus the fdt from bloblist should
> > > not be overridden with the ones from board or env variables.
> >
> > Why is that? The board can choose to override it, if it wishes, but in
> > general, if gd->fdt_blob is already set up, it should return -EEXIST
> > from board_fdt_blob_setup().
> >
> First, if a board is running in a "stand-alone" mode, there should not
> be a transfer list passed from the previous boot stage.
> Secondly, overriding the transfer list with the env variables does not
> make sense, since booti, bootm and bootefi are actually using the env
> variables to get the fdt when launching to the kernel.
> We need to do the opposite way - override the env variable with the
> one pointing to the bloblist fdt (See my patch [2/2]), then all boot
> commands can work with the transfer list.

OK, but now we are going back to the OF_BLOBLIST thing that I did 18
months ago and ended up being the major reason I had to create my own
U-Boot tree just to get my boards working.

Anyway, Tom has agreed to let me maintain bloblist (and maybe fdt?)
again, so I am going to send a series to 'clean this up' as Ilias
would say. Let's see if that passes muster, because I do agree with
you that if the devicetree is in the bloblist, it should be
definitive.

Re your second point, do you know why we have fdt_addr? Is it just for
the distro scripts? I'm wondering if we could restrict the use of
fdt_addr to just the places that actually need to use environment
variables.

Regards,
SImon