[TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages

[Simon Glass]

Hi Grant,
On Mon, 29 Mar 2021 at 23:19, Grant Likely <grant.likely at arm.com> wrote:
>
>
>
> On 29/03/2021 08:42, Simon Glass wrote:
>  > Hi Raghu,
>  >
>  > On Sat, 27 Mar 2021 at 03:59, <raghu.ncstate at icloud.com> wrote:
>  >
>  >> Julius, Simon,
>  >>
>  >>
>  >>
>  >> It appears there are opinions you carry around UUID being complicated,
>  >> bloated, code being an eyesore, parsing these lists early with
> MMU/Caches
>  >> disabled, calculating checksums etc. While there is certainly a LOT of
>  >> truth to those statements, these concerns need to be put into
> context and
>  >> may not necessarily apply to all platforms running TF-A. Standardization
>  >> and interoperability may be valued more on some platforms and some
> of the
>  >> bloat and performance issues may be worth those tradeoffs. Some of these
>  >> concerns may not even apply on powerful CPU’s and SoC’s with lots of
>  >> memory. Also a quick grep for “uuid” in the TF-A repository shows that
>  >> there is significant use of UUID’s for FIP, some SMC’s, secure
> partitions
>  >> etc so use of UUID is not something new to TF-A.
>  >>
>  >
>  > Fair enough. I hope, though, that if we can agree on a simple
>  > implementation like bloblist, then it becomes the standard and we can
> move
>  > away from the problems you mention with UUIDs.
>
> Ummm... I don't follow. How are UUIDs either complex or bloated? A UUIDs
> is simply a 128 bit number that is matched using a fixed length compare.
>
> What I like about the UUID scheme is it has collision avoidance built
> in, and it is adopted across multiple projects.

It's partly the UUIDs and partly the code that results (see earlier in
thread). But this is off-topic really, so I won't continue here.

- Simon