Clarification on Bloblist Initialization Settings

[Simon Glass]

Hi Harrison,

On Fri, 15 Nov 2024 at 05:49, Harrison Mutai <harrison.mutai at arm.com> wrote:
>
> Hi Simon,
>
> Thanks for the clarification.
>
> On 14/11/2024 22:06, Simon Glass wrote:
> > Hi Harrison,
> >
> > On Thu, 14 Nov 2024 at 13:41, Harrison Mutai <Harrison.Mutai at arm.com> wrote:
> >>
> >> Hi all,
> >> I wanted to clarify some details about the settings for initializing a Bloblist (i.e., CONFIG_BLOBLIST_ALLOC, CONFIG_BLOBLIST_FIXED, CONFIG_BLOBLIST_PASSAGE). The documentation states that if CONFIG_BLOBLIST_PASSAGE is selected, it uses the bloblist in the incoming standard passage.
> >> Does this mean that the bloblist is used in-place wherever the previous stage places it? For example, if TF-A passes a bloblist at an address specified in the platform's boot parameters, would this mode use the bloblist in that location?
> >
> > Yes that's right, but if BLOBLIST_SIZE_RELOC is used, U-Boot may relocate it.
> >
> That's what I thought but was slightly tripped-up by the wording in the
> documentation. Correct me if I'm mistaken, but it doesn't appear to be a
> supported use-case in U-Boot currently? From what I can see,
> bloblist_init assumes either BLOBLIST_ALLOC or BLOBLIST_FIXED.

Ah, I see.

Yes, you are right. The xferlist_from_boot_arg() side of things looks
like it needs a bit of work. We should be simply accepting what is
passed in, not relocating it to the fixed address.

> >> The reason I ask is that I'm preparing some patches to add bloblist support to vexpress64, and I'm looking to configure this platform without specifying BLOBLIST_ADDR or BLOBLIST_SIZE (i.e., automatically detect these).

OK, well see if you can tidy it up a little.

> >
> > Yes, that is a better way to do it, now that we have the ability to
> > pass a bloblist between phases.
> >
> >
> >> Thanks for your help!
> >> Best regards,
> >> Harrison
> >>
> >> IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
> >
> > I hope not!
> >
> Argh - apologies for this!
> > Regards,
> > Simon
>
> All the best,
> Harrison

Regards,
SImon